Hard to think of anything that might have changed with just the change of a clutch. But someone should come up with something.
Never heard the term "float" with a crank, but if he meant fore and aft travel, there's a few thousandths acceptable movement and Ford engines usually stay that way for their whole life. The one thing that will wear out the thrust bearing surface however is riding the clutch. If you and your dad spent much time with the clutch pedal pushed down, waiting at lights and such, then you could have put excess wear on the thrust surface.
And that's usually in the forward direction, so not sure if that would allow the clutch/flywheel to bind on the starter, or not.
Can you describe the binding? Is it just a sound? Or is the starter actually stopping when it's trying to spin? Have you checked your battery and connections for good contact? Lots of things can deteriorate in 12 years.
Paul