By putting a Chevy (any size) in your Challenger you can kill two birds with one stone (or swap)..............you will piss-off both the Mopar and Chevy camps. So to repeat RoswellGrey's question.......why bother. And, who will buy the vehicle later with it's mis-matched engine/body combo? Plus you are looking at all kinds of custom work, such as engine mounts, Trans mounts, wiring, etc...and the list goes on and on....and for what...a freak? You would be way ahead by staying with a Mopar engine for your Mopar.....
(But, having said that.....it's your car to do with what you want....)
(I do remember someone dropping a big-block Chevy in a 1970 Challenger back in the 80's, so it can be done.....)