Convert my '74 or sell it all and buy a '70?

yeah the reason i said pick the one with the best body and convert that is because if the body is bad underneath you need a roto and have to pull every single thing off the car so you can flip it & spin it around and work on it... ultra pro's also send it out on a roll back when it's stripped down to the inner shell and get it sandblasted before they start welding.

that is big work, so starting with the best body will save you months and tons of work. full off resto is either a long long process or lots of cash