Yes, the center bore is important, needs to be done on a lathe or mill and setup true to start with.
3500HD will have 5/8" studs.
Anything with this bolt pattern after 1956 will have 5/8" studs I'm sure. My memory is a little foggy on the earlier years but I am sure at some point early on, perhaps 30's or 40's they had 1/2" studs with this bolt pattern, and interestingly enough early on also an even smaller center bore in the wheel.
