The whisky itself should still be drinkable, so long as it has not oxidized by a
significant amount of air entering the bottle...Just to be sure that your bottle
is actually "manufacturer full" (something alot of people assume to be true,
due to it's unopened condition), the content-level should be level with the
lowest point of the Foil-capsule covering the top of the bottle.
***If this is actually the case, this would be a very rare condition to find a
1929 bottle in...most bottles begin lose a little bit (the "angel's share") even
after only a few years.
The whisky itself will not have changed in taste since bottling, and will be
much like any curent bottle you buy from the store today.
As for validating the dating of the bottle, I would need several photos of this
to be able to correctly verify the production date for you.
Such photos should include the following:
1) Top of the bottle (Cork/Cap area looking down)
2) The Front-label of the bottle (full bottle shot)
3) The marking on the bottom of the bottle
4) Any addtional labels on the sides of the bottle
If you can forward these photos to me, I should be able to get you both a
verifable date for the produciton of the bottle, and it's current market value.
Walter C Hurst