I have a GnG running on a SFII PCB here, I didn't do the GAL/ROM burning myself though so can't offer advise on that. Form what I can see from poking my head in the cab, the GFX ROMs are 27C4000G and the program ROMs are 27C4096. Mine is using a different B board though, a 91635B-2.
The roms that go in those slots are 27C4096G's (silkscreened on the board), but I don't know what their placement would be. I've tried this on my spare WW board and had scrambled graphics every time. The sound and gameplay are there, though. I suspect that there might be a different PAL/GAL necessary to make that board work for the conversion.