Here is a patch which converts the mapper in Dr. Mario from MMC1 to MMC3.
Dr. Mario (Japan, USA).nes - NOINTRO
CRC32: b1f7e3e9
MD5: d3ec44424b5ac1a4dc77709829f721c9
SHA-1: 01de1e04c396298358e86468ba96148066688194
SHA-256: 30b385456dada4ed242f383c7fabc8200d7529c273bb4c15f8cadda8a2449031