He's tuning his guitar DOWN to G, F# and F? Guitar players... :rollno:
BEADG should be all you need to work with. If he's going to cover sounds so low in the spectrum, I would try to go up instead of down.
You can try emailing Bill or Mike the serial number. They might be able to tell you. But from what I remember, the year should be somewhere in the serial number. Mine is a 98.