Well Aidan that is about as much evidence that we need really. If the label and print are consistent to the time then it is a very good indicator.
I was a bit sceptical too at first but the provenance of story seems to fit logically together. Which any antique expert will tell you is half of the verification process and with Aidan's research on the label makes it sound like it is genuine.
Just looking at the pictures of the empty bottles ... most are stained and discoloured but only where they have leaked and yet the bottles are still in very good condition and even one of the half empty one seems very clean. They were sealed in boxes and also wrapped in straw and if kept in a cool dry basement it is not unreasonable to think that they would be fairly pristine.
In relation to the spelling of whiskey I would not overly worry about that either as both were very much inter-changeable back then but the main one used in the US would of been Whiskey. The bottom label could well have been out on by the bottles and the Taylor label put on by Taylor & co. As is today a lot of spelling of whisky is spelt whiskey in the US media by those who are not fully aware of the difference.
In relation to ABV that is a more interesting one. The Proof system was used by both the US and UK but they were not the same proof systems. Further US Regulations states that liquor labels must state the percentage of alcohol by volume while allowing the Proof system also. Now the trick is to figure out when ABV & Proof systems were introduced. It seems the US has always honoured the Proof system and maybe that was simply down to making life easier with imports from the British. With the likes of Gin from England, Whisky from Scotland, Whiskey from Ireland and even Rum from Jamaica. All these popular drinks were under the stewardship of the British Empire. But did it also honour the ABV system???
I bought a very old bottle of Hennessey as a present for a friend once and it was in the metric ABV as one would expect from a French company. So I would not dismiss it totally with out further research.
It was first measured by the dilution of the spirit in gunpowder.
I wonder what bright spark came up with that (excuse the pun)
Then from the 1740's till 1816 the UK customs used Clarke's hydrometer to determine the proof of a spirit.
From 1818 till January 1980 the Sikes hydrometer was used and the standard was still measured in Proof.
An easy way to calculateUK proof to ABV was to devide by 1.75 that is why you often see bottles at 70 proof but are actually 40% ABV
However the US system was slightly different. The proof system was simply double the ABV which means that they could very well have been using the Metric ABV as a base to proof readings.
Now it is universal and the IOLM scale or the Gay-Lussac scale is used measuring ABV (alcohol by volume) and is expressed in degrees not proof.
Food for thought