That is one of the last persons I would trust. Vivid racing has nothing for these vehicles.
You really need to have a valid analysis of what is wrong and from what I read here, trust your instincts.
The only aspect of that transmission I am aware of having a problem is fasteners loosening on the rear mainshaft bearing retainer. Allows the mainshaft to move fore-aft with throttle changes in all but 4th gear.

If your transmission shifts well, do not break it.
If it has a bearing problem, that will be different in each gear and differing throttle.

A clutch release bearing, noise generally changes with foot on or off.

I would not pay thousands if it is just a $20 TO bearing.

The real decision for clutch work, pull the engine or the transmission. I think the engine is easier on that rig.
That transmission/Tcase is fargging heavy and does not want to sit on a jack. Because of the Tbar crossmember the trans needs to come forward.