I've had only a cursory look at 'Nancy' as I'm stuck in the middle of a complete revision of several week's work checking all 72 word sets -thanks to you getting me on the straight and narrow.!
None of them fit the scansion / metre of the tune RVW noted. Now I read stave, solfa, shape-note, chord charts and tab, but hesitate to try to create abc.
Think 'He who would valiant be', or as we folkies say, 'The Captain cried, "All Hands!"' and in G and 4/4 it's
D, | G A B A G | B D g F# | E D B G | A
1 | l.5 .5 .5 .5 l | l l l 1 | 1 1 1 1 | 3
That might convey the tune, though it wouldn't work in a proportional font. Bring back tapewritters!
I'll stop now.