The clutch disc has failed to quit spinning.
1) Are you sure you have enough clutch-plate departure.
2) are you sure the input shaft had room in the back of the 360 crank,
3) did you test-fit the input shaft into the installed and lubed pilot bushing.
It doesn't take much friction to keep the input turning, and if it doesn't stop, there is no way the brass synchronizer rings can match speeds to the parts on the mainshaft...... which are stationary........
