Dating them can be a puzzle. Even if you assume that tuners are original, there are a variety of factors to consider- frets, stamps, decal, headstock...
If the strings you are using are designed for C, tuning it down for G might be a little flabby, so you have to see what works for your instrument and...
Interesting......while I know some like a low G soprano, I have read that acoustically it is too low to resonate well with the size of a traditional...