I’ve had this one knocking around, half finished for years. The version I’ve ended up with diverges from the original quite significantly. As well as being shorter, the fast section is completely different in terms of notes.
The most important thing is to vary the tone between the guitar and the banjo – otherwise it’s not a duel you’ll just playing the same thing twice. There are a bunch of ways you can separate the two. For the city guitar I’ve played open strings wherever possible and picked and strummed mostly with my thumb around the start of the fretboard. For the rusty, backwoods banjo I’ve used more fretted notes and picked/strummed with my finger near the bridge.