Here is a patch which converts the mapper in Donkey Kong from UNROM to MMC3.
Donkey Kong (World) (Rev A).nes - NOINTRO
CRC32: E40B593B
MD5: 40319CAD12C80FC095901EB0182DF838
SHA-1: D8DFACBFEC34CDC871D73C901811551FE1706923
SHA-256: F9F026FD3560EEB03BE9F6D1EFA329B4C71D562CAF06D4A5A691E5342F8DA8E6