Rich,
My guess is that you could use either clutch-assembly/flywheel set inside the 53 clutch-housing. Just match the clutch-assembly to flywheel (I do not know if the diameters of the clutch-assemblies were the same on 53 216 and 54 235).
There are also two sizes of throw-out bearings.
Maybe someone will have advice one which might be right (and conform/correct my advice).
