ongaro -
If you don't want to further lower the stock's value then DON'T sand the existing glossy finish off!
It will be MUCH better to strip the finish chemically. If it is shellac, then all you need to strip it is alcohol. If it is varnish, you would use lacquer thinner (use with gloves and outdoors). If it's something else try various strippers on a small out of the way spot.
The point is, it will leave all the remaining wood and you could use some 0000 steel wool for final smoothing which will not remove the wood, but leave it ready for a good alcohol based stain followed by either Tung Oil or Linseed oil (The former is best - it weathers well, and the latter is more historically original, but does not hold up without re-application often).
RonJon
