A man in his 40's looking at a '70 442 convertible with his son said "you don't see many 442's, people use these and clone them into GTO's, GS's and Chevelle's"
Actually Dynacorn, the company that makes the reproduction Camaro and Mustang shells are doing 70-72 GM A bodies now. 1 Shell for all 4 cars. You have to add the roof panel/quarter ect to build which car you want. So it can be done but its a whole lot of work to do on a used shell.
Its no different then building a Demon from a Duster.