Ford 272 C.I. runs low 11's. Why do Mopar guys need 408's?

Who said anything about weight? Not me. I was talking about header fitment, engine mounts, ease of spark plug removal, trans has to change, etc. where a guy with a 318 could build a 408 and drop it in.
Like I've said before most of this comes down to personal preferences, compromises, to me that's a small price to pay. To me spending all that money to only end up with a 408 but that's me but doesn't have to make sense same with someone building /6 to a 318 etc..