49 geezer,
I'm calling on my memory banks, but I'm pretty darn sure there was a long and a short throwout bearing. Chevrolet usually used the pressure plate with the multitude of flat fingers and the short throwout bearing. Not sure, but I thought the other type, with the three arms, was referred to the Borg & Beck type and it might have taken the long throwout bearing.
You are very hot on the trail of a solution, and when someone pops into this thread that has been down this road recently, the answer will be revealed. Anything more from me will be speculation and confuse the issue...as usually happens. Good luck.
Stuart
