clutch not disengaging..........argh.........

There are all kinds of "little gotchas" but most of them are !!doh!! simple once you find them

Clutch disc in backwards? (Some won't even fit that way)

Clutch disc or even pilot shaft can be stuck in crank / flywheel, rust, etc

You sure the crank is deep enough and that the pilot shaft is not bottoming?

Otherwise, get under there and look, that's the only way!!

With a helper to depress the clutch you should be able to get a feeler in between the disc and pp/ flywheel. I don't remember offhand, .050" ?

There's bent/ broken linkage, I've had one of the levers "crack" the Z tube and bend. Take a look at your linkage. "generally" leverage of this type, for maximum travel, "wants" the pushrod and lever to be at 90 to each other at mid travel.