We don't want you bow tie boys around here!!
Welcome to the forum. Put whatever motor in the car you want. One of the most famous Cobras here is powered by a Viper engine. It also just so happens to be up for raffle!!!!
I'm not the mechanical expert, but I think most kits, with some possible mods, will accept most motors. I'm not sure of who has what kit, but I know of Cobras with...SB chevy, BB chevy, mopar, turbo Buick V6, Lexus V8, on and on....
Welcome and best of luck.
Steve