This sounds like a great project! Is there a specific low cost GPS that you'd recommend? Sounds like the wiring should be trivial (I gather you could help with this). I wish I had the software smarts to do the control and display for the Empeg. Seems like it should be pretty straightforward for someone who's familiar with the software innards of the Empeg.

Any idea if there's enough bandwidth in the CPU to manage this while playing music? I get the impression that the processor has a lot of available cycles.

I'm kind of surprised no one has done this yet. It would be a lot cheaper than adding a tuner (at current prices!) and, IMHO, a lot more useful than things like more visuals or most of the recent feature tweaks.