CNC was a firm located in San Diego that supplied Dennis Quella with his aluminum clutch master cylinders.
The OEM center to center clutch master studs are roughly 2 inches, but the standard spacing for the CNC master used by Dennis was 2 1/4”. Dennis arranged for a batch of them to be made with the necessary OEM spacing, but they were only available through him and not directly sold by CNC. You see a lot of these, or close cousins, on many Panteras. Shortly before CNC ceased operations I purchased a 3/4” master from them, made with a S&S sleeved bore.
The modification to the mounting holes by SACC is far from a precise, machining operation. I modified my SS master mounting holes very easily with just a good rattail metal file.
In short, just about any aftermarket three-quarter inch bore aluminum master can be easily modified to fit the OEM studs. A cast iron/steel mounting base would be more problematic, however.
And of course, one advantage to a aftermarket replacement is the ability to purchase from an established firm having a respectable track history of being able to deliver quality components……😉
Larry