I have found that w/the US NTSC vers. of Wild Arms 2 only the 7502 PSX Bios will run it, at least for me. I've tried several other bioses w/this game (obviously I have the game) and none of them work. The game would either hang or refuse to load at all. Only the 7502 would load it for me. So, you might want to listen to what the other members and I are saying, give the 7502 Bios a try.
I think you'll be glad you did.