I managed to get it to work by patching it to a pre-patched AshGray 3.6.1 (which was from the Fire Red ROM I was getting the error from, so I don't know what's up with that)
The game glitched out at Tangelo Island and Team Rocket kept saying their post-blimp dialogue over and over, creating an infinite loop, however I did explore the new maps using EliteMap and AdvanceMap, and I put together a large map made up of all the map areas combined, and I must say that it matches the official layout of the Orange Islands to a tee. I hope you will find some way to transport Ash to the northern section of the Orange Islands, so any new maps won't overlap areas covered by the existing ones. (if that makes any sense...)