Gen 2 LT1 cars have a clutch fork and T.O. bearing but are "pull" clutches, not "push".
The slave cyl mounts to DS bellhousing and pushes the fork which pulls the T.O. bearing from under the PP diaphragm to disengage the clutch.
OP
The most likely cause is you still have air in the hydraulics. The MC/Slave come as a sealed unit but you can buy them separate but that requires tedious bleeding which when done with MC & slave installed can be problem.
I always bench bleed the system and install it as a sealed unit because the MC installed at the angle it is typically will trap air in MC if not pre-bleed.
You can try bleeding system installed by letting the slave hang and you pump the slave piston by hand in short strokes while someone up top watches reservoir (MC) for bubbles and refills
This assumes you don't have FU hydraulics and or a cheap no name clutch (ebay??)
Sometimes the fork itself is bent but rare. Does it clip in to the ball stud on trans face correctly. It should be about flush with the bell housing opening (pic)
Do you still have the plastic cap on end of slave piston? (you need it) or clutch won't disengage which is the issue you have