Get Kerr's Caledonian Collection for the piano (still in print after about 120 years). Lots of Scottish dance tunes. From the 1760s on, almost all Scottish dance music was first published in keyboard arrangements. Published single-line melody arrangements for the fiddle or flute only took off in the middle of the 19th century.

Cape Breton piano accompaniment has evolved into a spectacular idiom in its own right. Also look up Violet Tulloch's accompaniments to Shetland fiddling - quite different but still innovative. But don't expect to find either in book form. (There are teaching videos on Cape Breton piano, I haven't seen them).