I've learned the hard way to always measure everything's good. Whatever was it the clutch (does the pressure plate release the clutch disc, does the slave cylinder have enough travel etc.) or anything else.. when the parts are modified or replaced with different parts.
Same thing with engines. One of the best ways to avoid stupid problems.
5 times taking the transmission out, clutch, some checks/modifications and assembly+clutch bleeding before I gave up and had my transmission and clutch, flywheel.. parts laying on my garage.
Took a break, and later noticed the clutch disc had worn unevenly causing all the problems.
Tho had two(!) leaking clutch slave cylinders at first. The first had been used and started leaking at some point, second was a new "LPR" branded slave cylinder and didn't hold fluid at all.. bad seal.
Third slave cylinder was fine and still in use.
My garage is too small for a car, so I do all my work on my driveway. Was good practise lifting that ~28kg ZF gearbox a few times under the car, and it took about an hour to drop the gearbox, do something for the clutch and assemble ready for testing.
Corvette transmission has the slave cylinder integrated to clutch throw out bearing?
That's a bit more difficult to check without dropping the transmission.
The bearing distance to pressure plate is easy to check, when you take out the transmission.
I've seen one throw out bearing/slave cylinder -thing started leaking (through the seal) after pulling transmission out.. was a Toyota Corolla or Avensis – don't remember anymore which one.
Glad it wasn't my job, and the mechanic working on it noticed before installing the transmission.
Usually they are quite reliable and hold for very long time.