McLeod's tech was not much help answering why the standard fork and throwout bearing would not work.
I'll answer this for anybody who is interested......
The diaphragm fingers will interfere with the input shaft collar when the fingers are depressed. The clutch will mount up and everything seems fine, but when the clutch pedal is pushed in, the collar interferes and wont allow full motion of the diaphragm fingers. To get around this, McLeod tells you to machine the input shaft collar off of the transmission and mount up a retrofit hydraulic throwout bearing.
For anybody here that has the equipment and ingenuity.... The diaphagm fingers can be shortened by a small amount and this situation can be solved. It would require some sort of cnc plasma cutter or waterjet with a turntable.