To actually answer your question...
Burns through transmission fluid? I assume you mean it leaks so bad you're bleeding fluid everywhere? Usually that's the torque converter lip seal failure. The seals can get old, hot, and brittle over 37 years' time. And then they start to break apart and cause little escape routes, which means hemorrhaging of fluid all over the floor when sitting for a length of time.
Typically, you would want to replace the front and rear seals, selector shaft seal, as these are all lip seals. Also the pan gasket. Of course you need to make sure all the sealing surfaces are good as well, as deep wear grooves in the torque converter or drive shaft can cause issues, even with new seals.
The issue you may have to watch out for is that the transmission's fluid loss could have caused clutch damage that never fixes itself. So seals alone may not be enough. Assuming the engine is in good shape, I would suggest that if you're going to yank the transmission to change a front seal, it may be worth it in the long run to do a quality rebuild on the transmission while it is out. 200s aren't difficult. You could get a TH350, but unless there's a good reason to do it, like upgrading stuff later, the stock engine shouldn't tear up a properly rebuilt 200 that was mated to it. Consider your plans for the car. If a TH350 meets your long range goals, then consider it. But if your goal is just to return it to stock, why bother? Talk it over with the transmission guys if you trust them. They can see/touch/feel your transmission and hopefully guide you in the right direction on what your car needs.