318 poly wide block

Dartswinger70 said
.... in a slave cylinder system the clutch will work untill the disc wears down to nothing, ....... The slave cylinder pushrod cannot move the pressure plate far enough to disengage the clutch, because the disc is worn too far. ......

This is WRONG. When disk wears the pedal goes UP, and the release is closer to the TOP of the pedal travel. FORGET clutch "worn disk" for the moment. Try and discover why it is not releasing as you have been

It's POSSIBLE that sand, gravel, mud, and "pieces of clutch disc" have become wedged in between the rear of the actual pressure plate and the framework of the pressure plate behind it known as the "clutch cover."

Here:

If enough "junk" becomes stuck between the pressure plate marked "plate" in this diagram and the cover, it could do exactly as yours is.