Mark IV transmission information

I “saved” a Mark IV by finding a Mark V engine and transmission. The transmission has a few missing teeth, etc. Will an XK 120 transmission bolt to this engine? Another solution might be to find new gears or another Mark V transmission. Any ideas would be appreciated.

Any trans with a serial number beginning with SH or JH will fit just fine. They were used in some Mark IV, all Mark V, some Mark VII and some XK120.