MIck - this might turn out to be a much bigger project than you expected. Setting new lyrics to old tunes is a very common practice, in many music idioms. More often than not, it isn't acknowledged, and may even isn't known to the lyricist. Many of Percy French's songs are hung on old tunes. I think that the Soodlum song books frequently acknowledge the source melody. I'm putting a "trace" on this thread because it could be incredibly interesting if folks "get into" the idea.