The tolerance for bellhousing mis-alignment is highly dependent on the transmission you are running. The later model O.D. 4 & 5 speeds really don't like to have their input shafts flopping around. Think about it, if you have 0.010" off-center from the crank centerline to the trans. register, then how far out is it at the input to mainshaft bearing area?
There is a angular check to be sure the trans. mounting face is square to the crank centerline & then a off-center check of the crank C.L. to the register bore.
Do a google of bellhousing alignment, there's a lot of info there.
I got into this after putting a MY6 behind the inline 292 in my '55 daily driver & experiencing some hard shifting & clutch chattering problems in the first couple months of running. Been 5 or 6 yrs. now, & no problem since.
Doug
