Would enlarging holes on the stock caliper mounting location be illegal under this rule?:
15.6 H. Brake calipers may be replaced, provided the number of pistons is equal to or greater than the original number of pistons. Caliper mounting brackets may be replaced to accommodate this change, but may serve no other purpose. Alternate caliper brackets must bolt to the original caliper bracket mounting location(s).
Becaause IMO, that seems oddly broad to allow such swaps without any additional clearances or minor modifications for new calipers or brackets.