SimonC: "Hmm, there's a thought. Could an emulator be written for this board to run native Beeb stuff rather faster than it's supposed to go?"
I like your thinking! But you'd surely only want to emulate the processor, and then you'd still have to send I/O and screen calls over to the BBC micro itself, possibly causing serious bottlenecks.
A BBC virtualisation solution running on a second processor system? It's so devious that you just have to get working on it! Once you've got your Beeb working again, of course.