Wheel stud knurle?

Putting longer studs on my '74 Dart bracket car. I have Mr. Gasket part #4311 which have an advertised knurle of .620" I measured them and got about .615" The old studs measure about .045" smaller. I believe these are the original front disc brakes for the car, they are LBP. The instructions say for a Ford you need to drill the holes out to 21/32. Should I drill out my rotors or is there a different stud that is the correct knurle?