I found someone to do the wiring. He worked on some Les Paul and on a SG too so he knows a bit about the wiring.

He also tells me that his father has a similar guitar and his got one pickup like the one near the fretboard of mine but on his guitar it's near the bridge. It's a 70's SG so I'm getting close to the truth now.

I just hope I could see a picture of the guitar to compare both.

I'll keep you posted.