Clutch identification?

[mr.lotus]

Engine out of the, 1963 Cooper. I know the car has the wrong engine and transmission (1275, full synchro remote). Pulled the flywheel clutch assembly, the clutch uses coil springs for pressure. As I understand, 850 early cars used springs? What needs to be replaced, to fit the later diaphragm assembly? New pressure plate? New center hub? Flywheel? Besides the speedometer and clutch, what other surprises will the car have for me? Could be that coil spring clutches were used until 1964? I don't want to go into the engine or transmission at this time. Perhaps replace the disk, seal and leave the coil spring clutch in the car, until the engine and transmission are rebuilt in a couple of years? Thanks, mr.lotus Mini in Arizona USA