Reply to "Clutch confusion."

Apparently you have a -1 ZF as would have been original to such an early car.  They use a modified 10-spline (basically Chevy) clutch.  The -1 bellhousing also differs some in internal clearances, which changes some of the parts options.  Assuming it's a -1, it has a shorter input shaft that requires a crankshaft extension piece inserted into the center of the flywheel/crank.  -1s typically run needle roller pilot bearings.  The supplied/balanced flywheel bolt pattern difference is something I would definitely recommend a Pantera vendor help you address.  I suspect they can also guide you on 3-finger or Centerforce style pressure plates (Centerforce generally has a lighter pedal pressure) to mate and clear the bellhousing, as well as the largest disk and material to best match your HP.  I bought my last -1 disk and probably pressure plate from Precision ProFormance owned by the late Bob Byars.  Don Byars at fullthrottlepanteras.com is probably your closest link at this point, or I think they formerly sourced their parts mostly from the same sources as Hall.  I have had good dealings with Dennis Quella at Pantera Performance Center including -1 clutch.  Never had clutch dealings with PPC (Larry Stock) nor Panteras by Wilkinson (Steve Wilkinson), but I'm sure they're all knowledgeable.