Is the clutch arm hooked right on the pivot mushroom?

The spec for the clutch mc and sc bores should be in the fsm. If so, you can compute the slave cylinder design stroke and measure the actual stroke and see if the hydraulics are all tight and air free. Take the ratio of (master bore/2^2)/(slave bore/2^2). Divide that ratio into the measured M/C stroke and the result is the slave stroke. This is just a second check on your blocked s/c test.

I bet on some kind of mechanical problem, like wrong thickness t/o bearing, bent t/o arm, missing pushrod pieces, improper t/o arm hookup, etc...