Myself, I'm not a big fan of cutting off one or both of those tabs. A long, long time ago, faulty distributors (rotor tip to distributor gear error) existed and that actually made it to production. Once that was discovered, all of them units were purged from the parts shelf and distributors were replaced on the dealership lot or on sold vehicles as they came in with certain complaints. Complaint being poor idle (weak spark) or crossfire at higher RPM's (max advance). You were either one tooth off one way or the other since rotor tip would never line up with #1 tower correctly.