Dimensions on the Greco are the same as a vintage TBird 2 hole and an Orville by Gibson TBird. My rings use #2 Flat Head phillips screws like the originals. I'm switching to nickel instead of aluminum.
How tall are your pickups? Genuine '60's Gibsons are 1/2" (12mm), 70's are 3/4"(19mm)...Orville by Gibson's have ceramic magnets and are 3/4" tall with countersunk covers and use guitar humbucker bobbins, looks like that's what you have.
60's rings have a larger outside radius, inside is the same.