You've got an exact understanding of how it goes with that wallet comment. Before you make a decision on what to ride, try to pinpoint closer the class structures. There always seem to be a class for the CB350, and it wouldn't be much fun if your 750 was badly out gunned by more modern bikes. Try contacting BigBob, he's been racing a CB750 for a long while. Either way though it's about having fun. Any past racing experience will help you on your bike.