Yeah, no shimming a Ford starter. But a nose cone breaking or cracking means the bendix gear is riding up on top of the ring gear. The ONLY way that can happen, unless something else got caught up in it. (In which case, you have maybe another issue, loose parts rolling around in the bellhousing, like a bolt that came out of the crank, or something.) Is a worn flexplate gear or bendix.
If you're flexplate has any wear to it to the point where you can feel a 'lip' halfway or even partway back on any teeth, it needs to go away and be replaced. I read broken nose cone, and I would replace it anyway, regardless, as well as (obviously) the starter.
Again, just my input, but I've seen this before on street engines and it's ALWAYS one of these things.
Ray