Here is most of the info, its looking like the 6 mm case bolt is really close to sprocket on early ones, so less room.
I measure from the outer case surface( gasket surface for shifter cover),over to the 6 mm bolt outside of the sprocket cavity. I got1.25 " for the 77/78..and 2.25" on the KO case.. Means less room.. I did not yet measure the 72 - 76 cases, and the size I posted is approximate.
Case Bearing boss width; this supports the outer bearing and seal.
KO ..25mm...... 73-76 ..32 mm.......... 77/78 ..42 mm
Bearing width;
KO no measurement. 73-76 ..17 mm 77/78. .23.8 mm
Seal width 7.0? mm
Between bearings, on shaft..this distance appears to be same between 77/78 and the 73-76 shaft.. Likely all years the same., but ID of bearings may differ **. 73 -76- sprocket shaft is 25 mm where bearings sit, 77/78 look like 30 mm, on the output side.**
So the real answer is, if a 77/78 shaft were in a KO case. You would have to run a narrow bearing, possibly with different iD, but due to the 6 mm bolt being in close proximity, might be hard to get sprocket on the shaft with cases assembled.
The later cases have the most room.
