This probably applies to you both, thanks.
It is a 9 bolt cover and large bolt pattern, as apparently that is the early case so I don't know if the later one will work or not.
I had to repair a 76 7 1/4 that had welded spider gears in it. I picked up a 64 7 1/4 from waggin a member on here. I can tell you in the open carriers, the spider gears will not interchange. But I swapped out the whole 64 carrier with the 76 and it worked? Don't know if this helps. But I would think if the SG's use the same bearings it would interchange?