Hey there Bleed, you'll need to look for a P-90 replacement, one of the guy's on this site (Benoit) awhile back had problems with a SG of his that someone had put a full size humbucker in, the problem was that the body cavity wasn't deep enough, so a full size humbucker is probably out of the question, Dimarzio has a new P-90 Super Distortion , Seymour Duncan has a P-90 Stack, both are P-90 replacement humbuckers, you may want to check out Rio Grande, I think they might have some type of P-90 size humbucker, if you are trying to keep everything as original and unscarred as possible this is probably your best bet............................