I may be against the grain here:
If the pivot for the clutch release in the bell housing is in the same place, (THAT is a Big 'If')
Then, It probably would be possible to put a foot clutch in a UT, but would need flywheel and perhaps starter, as well as clutch shaft, clutch shaft bearing cover with the sleeve for the release bearing to slide on, throwout bearing, throwout bearing return spring and whatever it hooks to, release fork, release fork shaft as well as new linkage back to the clutch pedal which would probably have to be fabricated.
It'd be the same difference between a UTS clutch and a UTI clutch.
You were asking a 'possible' not a practical question weren't you?