I don't think other makes have "problems" with the motors. RF, DRB, and Tornado use Ford crates as well. Just different designs.
It is just that from a performance standpoint you'd want a good road race pan with baffles to prevent oil starvation high high g loads - thus off with the Ford part. On some of the cars the Ford pan sticks down a bit too far.
If you have to use v-belt on the front dress, which some makes do, then the cover might not work for you. RF and CAV both have serpentine or v-belt thus can accomidate either.
For me the point is if the car is going to be a $60,000+ GT40 replica, then put a a strong motor with Ford forged internals that can live along life - either hard or soft. The Ford motors just don't seem to be such a good bargin.
R