I began to go into this a little and then realized the info I want is the bellhousing drawing for the five bolt engine, so obviously the 1965 up six bolt info is not useful.
I have a five bolt bellhousing whose transmission bearing retainer bore some "clever" fellow enlarged with a die grinder, by the look of it. Presumably this was to fit the later transmission with its larger retainer.
I want to locate this bellhousing by its dowel holes on a milling machine, then clean up the bodged bore. I will then make up a ring to push into this new cleaned up bore, to restore the unit to original specs.