As you say, the limiting factor when applying the load is the strength of the 2 5/16 studs screwed into the flywheel. I use an alternative method that has always proved successful. You need a 3" dia x 5/8" thick steel disc drilled and tapped to take a 3/4" x 20 tpi bolt, a suitable length 3/4" x 20 tpi bolt, a second flywheel, and 6 5/16" allen screws.
Leave the crankshaft nut loose by about 3 turns. Start by undoing the six nuts on the engine side of the clutch guide pins (working through the clutch inspection hole). Undoing the nuts will cause the clutch springs to load up the clutch thrust, thus making the crank stiff to turn. With all 6 nuts removed, the pressure plate (complete with the guide pins) and clutch disc can now be removed. Now fit the 3/4" x 20 bolt through the centre of the second flywheel (from the back), and screw on the 3" dia disc. Bolt the 2 flywheels together (face to face) using the 6 Allen Screws (you may need heavy duty washers under the heads). Use an air ratchet to tighten the extractor bolt until the flywheel pops off the taper. At this point, unbolt and remove the second flywheel, then slowly undo the crankshaft nut to fully unload the clutch springs.
Hope you find this useful,
Regards,
Eddie.