John McCain / Bob Smith (R): 50.2% PV; 334 EV
Bill Bradley / Bob Kerrey (D): 46.2% PV; 204 EV
Ralph Nader / David Cobb: 2.2% PV; 0 EV
I don't think Nader would do any better against Bradley, and in fact would probably do worse. Bradley would be anti-establishment and liberal enough to reel in progressive Dems that defected to Nader in otl 2000. Bob Smith would be an interesting choice for running mate, though I think McCain's best bet might be Elizabeth Dole (and IIRC she was his pick otl as well).
Nader would probably still hit the 2% mark though, and would continue to be a force to be reckoned with come 2004 without costing Gore the election in 2000. And it would probably be one of the cleanest campaigns in modern history; IIRC McCain and Bradley respected each other and were good friends (maybe worked on each other on campaign finance?)
It'd be an interesting scenario for sure