Just refreshing this thread to say I have found several versions of the song at iTunes. Haven't decided which one to buy yet, but I've gotten a pretty good idea of the entire tune from listening to the 4 or 5 different sample clips at iTunes.

I'd still like to find a MIDI if anyone has one.

I had spent a lot of time trying to find the song under the title "Maggie, Dear," but it seems it's usually called "I Never See Maggie Alone."