I think when hot rodders started swapping engines there were plenty of Fords to go around. Now don't get me wrong I like Fords, first car was a '31 Model A, currently driving a '97 Tbird 4.6. But I don't have a problem with anything , and I mean anything in a Ford, were talkin' Hot Rods here.
Now when it comes to anything else I've just got this thing about, "Hey , what are ya doing here? Couldn't find the right engine for that thing?"
1933 Plymouth with an Olds ? NO. Now this is just my opinion. http://www.californiaclassix.com/archive/33_Plymouth.html
I've seen all kinds on Plymouths at shows, walking up thinking man this could have any number of MOPAR engines in it. Nooooo a Chevy ? What's going on?
But the nostalgia thing tells me it's ok to put any number of different engines in a Ford.