biggest PITA is the slapstic, would either need a PAL programmed up to emulate each games one, or hack the code to all use the same - either way, a pain to test.
it would also need a very large PCB made up, the carts are HUGE.
but anything is possible, just don't see this one being economical - probably easier to re-do the entire circuit into one of the FPGA replay board - would work out cheaper as well
reminds me, Egg said he gave Rav my spare Atari System 1 motherboard to Rav - Rav if you are reading and this is so, let me know (cheers)