New Member with a big question

Young man I think Floyd pass along some sound advice to you. Get yourself a good sound dependable daily driver to get you to work and around town. Put your Duster under wraps for the time being and invest your time and money into it over a period of time. You can save some cash by getting your tools out and tearing down your engine. Drain out the bowl on your carb, take it off and protect it from rusting/gumming up, take off your intake then your heads. If you do have a cracked head the crack my be readily apparent but if it isn't you might be able to reveal it by simply dye checking it, which is cheap. If that doesn't reveal anything you can take them to a shop and have them checked out utilizing other methods which you don't have the equipment to do. As long as you have another ride take the time to pull the wrenches on the car and learn it top to bottom. Even if you don't do a lot of replacement of the rotating members in your engine (crank,pistons,cam etc) take it apart, inspect learn how to use a set of outside and inside micrometers, depth gauges, calipers and other useful precision tools for rebuilding engines, transmissions, rear ends etc,etc.
I go with Floyd that you can get a new transmission for less than $ 2,500.00. Might take some looking and patience but eventually you'll find one. As far as body work if you have a technical school in your area check to see if they have an auto body course that you could sign up for and take your car as your semester or more project. Use their facilities, tools and teachers to do your drivers side quarter panel plus any other areas of body cancer that needs attended to then put a nice paint job on Duster. I have a dozen old muscle cars and once in a awhile I don't feel like paying a body shop big bucks to replace some floor pans or trunk sections or quarter panel so I go down to the local vo-tech pay my meager shop fee, load the car body on my rotisserie and take it over there to do a little resto work on it. I have a 69 GTX and a 69 Mach 1 I am going to do some work on over there.

Last but certainly not least. Keep the keys in your pocket and tell whomever wants to "Borrow your car to run an errand" that you will be glad to run em around for a little gas money but they are certainly NOT going to be driving your ride without you in it behind the wheel.

Just some suggestions for ya

The CudaMan- Ron