I haven't even begun to think/worry about that yet. Hopefully it just works. Ha!
In all seriousness, I'm literally waiting for FedEx to deliver my 'scope (hopefully Friday) so I'll have a better idea then for what I'm dealing with. I do know that at 9600 baud it seems to kinda-sorta work, but I do seem to be getting some corruption, but that mostly seems to be due to the timing differences from what I can tell/guess. So it appears the line is pretty clean.
That being said, I haven't tried it with the bike actually running yet, so things could get a whole lot noisier once those coils start firing.