FWIW here's my work in progress crib sheet for Original A-body Master Cylinders & Bore.
Feel free to add, question or correct (especially if you have a documented source).
years___Application_____________p/n_______Bore
1966... Fixed Ft calipers, Manual................1"
1966... Fixed Ft calipers, Power..................1"
67-70.. Fixed Ft calipers...........2808600.....1"
71-72.. Fixed Ft calipers...........3461178.....1 1/32
73-74.. Floating caliper, Manual..3580146.....1 1/32
73-74.. Floating caliper, Power.. 3580112........15/16
1976?...............................____4647..........15/16