Just so I'm 100% clear on an 8 3/4 swap!!!

Before making that drive, I'd have the owner measure the rear to make sure it's an A-body rear end. 43" center to center on the perches, overall width, small bolt pattern, brake size, etc......A factory 8 3/4 would be very rare in a '65 A-body. I've seem many swapped in, even at the dealer when the 7 1/4 broke under warrantee, but, I've never seen a genuine factory one that year. It's even fairly rare in the '66 models.