The original recording by Amede was on a D accordion, played on the push key (D).
I also like Steve Riley's version, which used a Bb accordion, played on the push key (Bb). It is much easier for mere mortals to sing the song in this key!
As to tabs, I haven't seen any for this song. I learned it from Steve's version years ago, and I don't recall it as being hard to figure out. I probably simplified it a bit.
I have been thinking of adding this song back into the repertiore again...