Even when buying Girling calipers, one needs to be careful. Apparently there were lots of Girling three-piston calipers with very minor differences in the castings. Example, my 1969 Ferrari 365GT 2+2 had the same (apparently) calipers. I've even seen them without the "G" on the single piston side casting.
My replacements fit perfectly, "HOWEVER", a tiny casting difference forced me to modify the disc backing plate on one of the front hubs. Additionally, perhaps due to rebuild "machining", I found that with new everything, rotors, calipers and pads, althought the measurements looked right, they were tight when newly assembled. I had to manually turn them for a couple of hundred revolutions before I felt comfortable that they will loosen up quickly when I drive it and apply the brakes a few times. At least, the left and the right are the same.
If I could do it over again, I would have had my old ones rebuilt instead of buying rebuilt ones.
At my age, I have finally concluded that not all my questions will get answered. Just be careful.
Tom Kizer