[B.M.B.C]

Visually a FE is period correct in 427/428 car, as is a 289 in a earlier slabside. But modern replica or reproduction cobras or what ever you wanna call them, can or will benefit from the cheap power/cubes available from 385 series big blocks if thats the route you wanna take.
One thing else i will add is that when the aftermarket really get there teeth into new gen mod motors like the coyote 5.0 with blowers and high hp outputs(650+), good gas mileage out the box will be the norm....