I don't now and have never bought the argument that once you start using modern suspesnsion, brakes, etc. etc. you've upset the apple cart and so now it's OK to run whatever modern motor you like as well.
It's NOT OK, in my opinion. You can tweek the the suspension and play with all kinds of variables through out the car, but the "motor" is the "soul". SOME Cobras demand certain motor's, other's not so much. ERA 427? Gotta be FE based, that's just the way it is. Kirkham, same thing. FFR? While small blocks are the rule of thumb, who knows what you might find lurking under the hood on any given car, no limits. FFR is pretty much a "no limits" car in all regards. Spice up the interior, go for some custom chrome wheels, heck, add a wing and some neon lights if you want.
That doesn't make FFR good or bad, it's just a reality check.
Now if you start going all "custom look" stuff on a Kirkham and add red crushed velvet interior, chrome wheels and a V6, your going to look like the fool you are.
Changing the suspension is one thing, changing the interior and messing with the motor choice is a whole 'nother can of worms!