Joe, the entire 4 vol set is online in several editions. Anything after 1740 should have the complete 4 volumes included.

Jack, I only have access to the Amadeus edition which would appear to be a facsimile of the 1792 edition but I can't see any notes of David Laing's anywhere. In fact there are no notes in the actual song section at all. I also have Stenhouse's Illustrations which do mention Ramsay in various places but not on p393.

What I have spotted though which I hadn't had a good look at before are all the appendixes at the back of the second volume of The Museum. Thanks anyway.