[Oldsguy]

Kayle, you got yourself a gem!

-Reverse ground means the positive battery terminal is grounded on the frame and the negative battery terminal is "hot" but I don't think your car has that, at least my '48 did not.
-It is probably a 6 volt system, how many vent caps on the battery? If there are only three then it is definitely six volt. That can be converted, that way you can replace the generator with an alternator as well.
-The glass might cost you some money. If you plan on registering and driving the car often most states make glass an inspected item. Some states have a certain status that does not require an inspection so you could delay the side glass replacement if the car is garaged. The windshield, of course, has to be replaced.
-Rust, it seems you expected that and have a plan.
-Interior, ditto.
-Suspension and running gear, as well as other Olds stuff can be attained. Check out these two names, Fusick and Kanter. Brakes should be the first thing to fix, even before you get the car running.
-Ebay has lots of little stuff often, I see replacement or OEM tailights for my '48 all the time on ebay.

Back to the turning it over, if you convert to 12 volt system first the starter motor will turn faster and that may help the engine start but if you want to be real careful about it take out the plugs and see if you can turn it over by hand using a breaker bar on the crankshaft nut in the middle of the front pulley. If you can that is good, you might also want to squirt some light oil into each cylinder to pre lube them. I would bet that the carb gaskets are dried out and you may have trouble with fuel delivery. You could prime it with a tablespoon of fuel and see if the engine will start, if it doesn't that won't hurt the carb. Also, go ahead and change the oil first. Let us know what happens.