In one Pantera I have a Centerforce diaphragm clutch and ended up taking out the clutch effort reduction kit because the clutch pedal tended to be very on/off. The clutch now works well and does not take much leg strength.
In another Pantera I have a McCleod long finger clutch and it was very difficult to press the clutch pedal. It took a lot of effort and did not seem correct. I added the effort reduction kit and clutch was immediately friendly. It would be difficult to drive this car without the effort reduction kit.