Well we just can't be having this!
Machining the pressure plate? Flywheel yes, never did a PP. I would suspect as long as it was no more than .005" the plate can make it up in travel . Although this would show up in holding ability, not shifting.
The 1/2" play in the linkage is normal assuming the pedal isn't sitting really low compared to the brake.
What are "finger nuts" exactly?
I guess the first thing I would do is check the clutch clearance and make sure the clutch disk can move.
With the clutch pedal depressed...If you can get a 0.025"- 0.035 feeler gauge ( 0.5-0.8mm) between the flywheel and clutch disk, AND you can spin the clutch disk fairly easy, that should be good starting point. Adjust the linkage for the clearance. Also- if you have one of the rubber bushing that engages the clutch fork, make sure it's in good condition, they tend to get squished. Personally I would chuck it for the all metal part. I digress..
While your there make sure the TOB ( throw out bearing) is the right size for your pilot shaft, and that it fully releases the fingers on the PP when the pedal is released. I mention this longshot only because of the two TOB sizes- no offense , but I've seen it done with the small pinion trans and large pinion TOB. Might as well check since your under there. The TOB should be able to rock slightly on the pinion cover it slides on.
If you have the clearance and the clutch disk will spin fairly free , i would check the shifter linkage adjustment. Those rods have to drop in the levers with no pre-load either way, and the right drill bit holding the shifter in it's neutral position.
If you have the clearance and the disk will not turn freely / independently of the flywheel and PP that could mean the input shaft is stuck in the pilot bearing. It's going to take some effort to rotate the disk but it shouldn't be much if the pilot bushing and input bearing are all working ok Listen as you turn it a slight dragging sound as the parts turn is to be expected but they should not be engaging each other or able to transfer any significant rotation. I guess the best way to put it is it needs to be loose to turn freely, but no, or not much, more than that. The disk should have a very slight play between directions of rotation as well. Not much, but it tells you the splines aren't stuck between the disk and input shaft.
Post back with what you find.
RC
4th generation B bodys- there is no substitute.
68 383, Street Demon 750, RPM top end,484/284/108 poo poo cam "-5 spd 4:10 SG, 4whl disk, Helwig Anti-Sway, Poly bushings,Firm Feel Box, HD Linkage, 1" t-bars, 7 leafs Springs