Hi, K
I had this box fitted to my crossflow 4/4 in the 1990's.
IIRC the clutch kit was for a Ford Sierra. Remember those? Same flywheel fittings as x-flow and splines for 5 speed box.
Of course, Caterham used x-flow with 5 speed box for many years, so they would be able to tell you more.
Good luck
Andrew