So say you bought a car that came from the factory with a big block and 4 speed. The thing is it has non of the above when you buy it. Would it be sacrilege to install a small block and automatic in it seeings a how that is all you had?
Think 69 Roadrunner 383/a833 car to a 360/a904.
I have put slant sixes into original 318 cars to get them running. What difference does it make and at the end of the day it's yours so do what you want.
My 71 scamp is an original 318 car but now has a slant six and I'm keeping it like that permanently, because I wanted another slant six car.