I purchased a 1965 SG online about twenty years ago for a fair price,and was told by either the seller or someone who worked on it that the guitar was originally a SG special (came with P90's) but was converted to humbuckers,but how can I be sure? The serial number looks to be 555966. I would like to restore it to original by replacing the humbuckers with P90's,but would there be an issue with wood around the pickup cavity making it appear 'unsightly'? Before I take this project on,I would need to confirm if the guitar started out as a SG Special or came as a SG Standard. Any help would be appreciated,Thanks.