i think a big block would be too difficult, but a small block is very possible. here aretwo options that could back it work.
with this kit you'll be able to install a v-8 and keep it FWD, eliminating the need for extensive body mods.
if you must go big block i would recommend building or extensivly modifying you existing front subfram to accept the BBC in a traditional north-south layout and using a TH425 out of a toranado or similar FWD car.
think outside the box people, it'* good for you.