I see what you're talking about in the Base Shop Data manual. In TM 9-1711 they give a measurement of 15/32" from the adjusting ring to the machined surface of the flywheel ring. After assembly this should get the pressure plate reasonably close to the height of Gauge 909020. I just did mine last week using the 15/32" dimension but then had to turn the adjusting ring out some to get enough clearance for the disk. I don't think that measurement is critical because once the assembly is installed, you'll probably be turning the ring in or out to properly adjust the clutch anyway.