New Kid on the block

Welcome! , not saying it's impossible ( maybe hangin' tough ) :D , but why wouldn't you just take the good stuff off the 67 and build the 68? Not too familiar with earlier A-bodies ( I understand that there may be small differences but I'm not familiar with them ) , but seems like less work to build the 68. Unibody inherently means that the frame and body are unified ( effectively built as one piece ) and are difficult to un-unify :lol: .
Having done some mild rust repair myself, make ABSOLUTELY sure it's ALL gone, or it'll come back if you decide to use the 67 as the base...