You have ruled out incorrect components, binding/sticky throwout bearing on the input shaft retainer sleeve, and your application does not use a fork return spring. I am assuming you have a good clutch pedal feel and the clutch engagement/disengagement is good relative to clutch pedal travel.
Fully depress the clutch pedal three times with the engine off and transmission in neutral.
Separate your slave cylinder from the belhousing without disconnecting any hydraulic hoses.
Keep your transmission in neutral, bypass your neutral safety start circuit and start your engine.
Does your thowout bearing still spin due to contact with the diaphragm spring fingers?