Well, the clutch was "slipping" because of a busted up clutch basket! When Dad and I unloaded the replacement engine from the back of his truck, it took a slight tumble to the ground. We caught it, or so we thought, and it was a gentle lay-down.
Turns out we busted up the clutch basket. I'm really lucky that it didn't explode when I was riding it!
This one ear was bent and not allowing the plates to move. We tried moving it back knowing full well it would break....and it did.
It was until we removed the basket that we saw that the rear of the basket had a crack as well.
Pulled the basket from the other engine and installed new plates (even though the ones in the engine measured out perfectly fine....it was the damage to the basket causing the problem) and now it all works perfectly.