Looked through my pictures and this appears (just based on the collection I have at the moment) that the change over at San Jose was around
Lowest VIN car I have record of with the beveled hinges 5R140504
Highest VIN with the square edged hinges 5R187778
What I found most interesting was that when you had one style (for example beveled) all the hinges on the car were all the same style. No mixing of the two styles which (from the supply side of things) is interesting since one might expect that the plant would use up the old and transition to the newer style as supply ran out or at some point mixed the two. Like bolt head markings in some transition ranges. Seems to suggest intent.
Do have one anomaly, a pretty late 66 built at San Jose that had square edge hinge. But only one
Focused only on San Jose based on the OP's need and original question
5R14050x
5R14745x
5R18777x
5R1965x
5R20693x
5R2796x