[Will]

Use the B-body spindles from a car that came with 12" brakes (not all B-bodies have 12" rotors), they are a direct bolt-in.

Then go buy a set of brake rotors for a mid-late '80s 1LE equipped Camaro/Firebird. These will bolt on and have the correct wheel stud pattern.

The only issue will be that the late model rotors are drilled for metric wheelstuds. You may end up using metric lugnuts for your front wheels, or you might be able to find a stud with a close enough knurl diameter and overall length to work by going to Napa and having them cross-reference the different studs in their books.