I'm running 4.75" redrilled 69 Bonneville rotors, since the desired US Mags wheels were not offered in 5 x 5. Had it done by a local professional machinist, since accuracy is critical, and the back of the rotor must be spot faced for the press in lug bolts, which can be seen on the existing 5" pattern. Also, the bearing snout must be turned down slightly, since 4.75" wheels tend to have a smaller center hole. There is plenty of meat in a GM rotor for doing both operations, so no worries. One hassle, bought a dual lug pattern wheel for a spare tire!
There is another option, Scarebird offers a bearing spacer that allows use of 1LE 89-92 rotors, which are already 4.75". These will likely not have 1/2" lug bolts though, a quick check on Rockauto listed at least one rotor with metric lugs.
https://scarebird.com/index.php?rout...&search=indian
https://www.rockauto.com/en/moreinfo...sn=870&jsn=870