I just picked up a rare 1987 Gibson SG-Z ... turqoise green mahogany body with pearloid pickguard, 25.5" scale ebony 24 fret fingerboard w/ split diamond position markers on a mahogany neck -- strings are secured body-through with a eyelets in a diagonal pattern. Its not mint at all and the volume and tone pots are not original; but it seems to have been played a great deal and still has that bar/cigarette smell in the wood and has an unbelievable tone There is a slight/mild concave (corrected) neck neck bow from the 4/5th fret to the nut that the adjusting the truss rod will not correct -- the truss rod seems to work well but changes mostly around the 12th fret -- its significant enough to keep the guitar from being setting up with a low action which I prefer. When you look down the neck you can see where the bow starts on the back of the neck, along the fingerboard binding as well as on the the fretted surface of the fingerboard. I can think of three potential remedies to address this issue (not being a repairman): 1) dress the frets (since they are high enough) and accept that they will be low near the nut ... or 2) do a complete re-fret and resurface the fingerboard to compensate for the bow -- I am concerned with this approach since you could be taking away even more wood which would otherwise be necessary to keep the neck as straight as it can be; or 3) do a complete re-fret and replace the binding with, say, ebony to improve structural integrity and reinforce that area of the neck. if such a condition is worth addressing -- or is it better left to another player who would otherwise be happy with a higher action?