If the slave cylinder is moving 1.5" when pushing on the pedal, It would appear the problem is at the transaxle end. With that said, 1.5" is a lot of travel, indicating that if the clutch was being disengaged, the pedal pressure would be very high (too high?), in other words, not have very good mechanical/hydraulic leverage.
Question, can this amount of travel be detrimental to the diapham in that it would pull the throwout bearing too far forward?