I don't want to give figures, but honestly, the guitar is probably not worth that much.
SG Specials are not that rare or in high demand; this one has been routed, so it will never be worth what a stock example will go for, especially as there is no good way to restore it.
I restored a 1956 LP jr that some sushi-for-brains routed for humuckers and a tune-o-matic. Even with the finish shot by the best vintage Gibson specialists I could find (and I know a lot of them) it will never be worth anything like what a stock Junior will be.
I could sell it, but it would not fetch much, and I tell myself that if I do, I will probably never have another 1950's vintage Les Paul. In fact, if mine had not been molested, I would not have been able to afford it when I got it. ;)
So I suggest enjoying your guitar. That is what I do with my old Les Paul.