"I don't play with English concertinas much - I find some easier to tune in with than others - Norman Chalmers's instrument seems more friendly than most. It would make sense for somebody playing Scottish music to get their instrument retuned to something like meantone centred on G or D; maybe Norman did that? "
in my opinion not a good idea, for a start what about a major , or some of the tunes in b flat or g minor.
if you want to do that get a 20 key g d anglo