What is a gallon unopened scotch whiskey worth from the 1960's?

depends if it is a single malt, blended, and the beginning quality. If it was bottom-barrel at the time it was bottled, it is bottom barrel now. If it is a very good single malt, it is worth slightly more now, from when it was made, but aging to a smooth, thus high value liquor, needs to be done in its fermenting barrel.