First of all you have a number of things in your favor! It was parked in the era of leaded gasoline! This means that the gas tank is probably still good, and probably won't have to be removed and clened before you can use car! Modern "gas" is a funny way to spell "crap"! It will not last much over 3 months in lawnmower or small engine tanks without starting to "rot"and mess up tanks and carbureters! In car- if low maybe you can get by for a year! Take 30 years with this gas in it, - probably cheaper to eplace entire fuel system from front to back including fuellines and fuelpump, carb.tank and sending unit! The only way around htis is using gas stabalizer in tank for stoarage,-(this is why you see so many mowers going to scrap!)- It's easier to buy a new one than get the fuel system all fixed up to make the old one work!
Now I am done with my praise for "new gas", - here is what I would do, - first of all I assume you have tried the engine to see if it is seized (turn crank by hand from front pulley, or using fan and belts), - just move it enough to see that it is not "solid"!
Next remove sparkplugs, and spray a little luibricant "spraybomb type" preferably non WD-40, (but this is ok if that is what you have), - if you buy a new can,they generally come with the little spray tube taped to side of can, This makes it easy to get it in through the sparkplug hole! UIse a liberal amount to make sure thrat there is enough in cylinders to well coat sides!-- this is to make sure any rust or stuff on sides of the cylinders won't cause undue pressure on rings, (and slow down cranking - or cause pistons to "seize" in beginning!) It would be wise to unplug wire from the ignition coil (unless this one alrady has the "HEI" coil on top of distributer)! -- This way you won't have "sparks popping "around on wires,- to maybe "get" you while working under hood --(especially if you have somebody working with you)!! Also it would be a good idea to unhook fuel line somewhere between carb and fuel pump, and hook a piece of hose on it - running to a container so you can get a sample and see how bad it is and determine if you have big or small probelms in fuel system (more about this later)!
Next thing I would do is to pull out the drain plug and put in new oil and filter, --don't buy "best oil possible" just yet, - plan on chaniging this oil soon after you get the car running!
Of course having checked and seen that the water is "full" in radiator, - (this will be replaced after you get the car running too, so don't spend much on it right now)!
Now if you have the things above taken care of, you can turn the engine crank over a couple times by hand (if it is easy enough to turn - meaning hyou can get to it to turn it!)-or you can now crank the engine over -- (this may be a little messy, as if it cranks fast enough it may shoot a little of the oil you put in cylinders out),-- continue cranking till the oil pressure light goes out, or oil pressure gauge reads oil pressure (and stops moving "up"!) ....Yes, some of these "archaic cars" had actual oil pressure gauges so you could tell how system was performing! Another pet peeve of mine, modern cars always have the light come on afrter the engine "craters" - so you will know tha the oil pressure "was bad"! Instead of letting you know that things are propgressing towards problems, and you can take care of them soon enough that you won't need a engine replacement (or rebuild- if you are "lucky"!)
Ok you have oil pressure, and have spun it for 30 seconds or so after it has stopped moving up! Don'r spin more than this amount of time (30 secs.)-- without a pause of about 30 seconds between cranking "spurts" -- this allows the bearings to "cool down" so that it does not damage the "babbit" in bearings (babbit is the actual bearing contact surface material between bearings and crankshaft!)By now the bearings are all "lubed up", and the valve lifters are (hopefully) "pumped up", -- you should have a sample of gas and know how bad or good it is!
Decision on what to do with gas has been made!--- If gas really bad and foul smelling and and looks almost coffee colored, it it pretty bad, - (but if it flows through the system to your container -that is good)! I would just get a gas can and pump all the fuel it will pump out oft tank. --- Next step is to get about 5 gallons of "premium fuel" (highest octane available), - and a couple cans of "Berryman B-12" most auto patrs stores and WalMart carry it! Mix these together and pour contents into gas tank! and you are ready to try and start car (after cranking till fuel comes from fuel line again)! Note if gas was "real bad", you can go ahead and try starting car, -- the gas will just pump ot faster if engine starts! If gas looked somewhat like gas and only smells modeartely bad you might just add "premium and berryman - in propartion to what tank reads for fuel level -- about 2 cans of Berryman and 5 gal of preium" to 1/4 tank of gas indicated! Tank is probably 25 gal total capacity!
Ok, we now have all the sparkplugs back in and hooked up, water in radiator , oil changed, and we are ready to see if engine runs!. Locate the "vent" on carbureter, - usually near the "post with "peg" that aircleaner sits down on and you screw the nut on to hold top on aircleaner! you can pour a "few tablespoons full"-- (maybe 6 or 7) into the vent and this will sit in the carbureter bowl.- When engine starts running this will feed fuel to make engine continue running - till it is all used up! If fuel looked good enough to use, -it will now pump the carb full and it will continue running (hopefully)!
Now the engine is running, (and valve lifters have quit clattering),- let it run for a few minutes (all the time watching so you can shut it off if anything is not working right -- you can see that charging system is working, cycle transmission in and out of park (if automatic), or find out if clutch plate is stuck to flywheel (from sitting so long)! After a good long while running at idle -- smoke will all be gone (from oil put in cylinders, gunk accumulated while sitting, and moisture in exhaust water will be "burned out", -- exhaust should now be fairly "invisible"!!
Brakes checked out ok? Now you can carefully testdrive it!
Drive expecting brakes not working, watching engine indications, and leave "loads of room" between you and everything else! Be ready to shut off engine quidkly!! If it passes all these things, then you can drive it over 25 mph in increments of avbout 10 mph - till you determine it is safe to try on "open road" at road speed!
I would reccomend that you do not go out on highway till you have crawled ounder the car and checked all the freeze-plugs to make sure they aren't leaking, and of course you have checked all the hoses and belts somewhere before starting engine!
All these things done, you should take to garage and have (oil and filter changed on automatic transmissin), Oil checked in rear axle and std transmission (and changed if they look like they need it! You now change oil in engine and put in good grade of oil you intend to use for a while! Do this while engine hot, -it has all the "junk" mixed with oil, and it will drain out easier to get clean!
Now you are ready to drive, -- contact me on Yahoo email, and I will give you tips on all the other stuff you should check,-- I play with old cars (oldest I have is 84 yrs old), so know a few "tricks" that help!