No nearer finding the full text, but this archive maybe clears up the Linn/Frame thing. Bill Frame was another Glasgow Music Hall artist and an admirer of Harry Linn, and writes about Linn while describing his own life story. There is a heck of a lot to read here, but a fascinating insight if you've the time for it. If not, fast forward to Chapter V, last paragraph of p42, down to bottom of p43. Frame only quotes the last 2 lines of the song. Frame and Linn

And another snippet of info from the Spiers family website: Tom sings the usual "Stoutest Man" version, as sung by Jimmy McBeath, but came across "The Fattest Man" in his research: says Harry Linn was a stage name, real name Andrew Crawford. That info was from Adam McNaughtan who has a huge knowledge of Scottish music hall songs. I occasionally see him at events in Glasgow, so will ask him if he has the full lyrics somewhere, next time I see him!