as long as the rpms didn't get to red line once it started climbing then you should be fine. the only problem you may have is the crank may need to be replaced if all the bolts holding the flywheel to the crank got sheered off. the force created to sheer the bolts may have bent the crank but not enough to see visually. as far as the gear box goes...........was it a rebuild a 5 speed or 6 speed you used to go with the swap?