If it were me, I'd try some of the stuff that is said to be +/- .0015" and is $20 for 8 feet. Now if it's a bit oversize, I might try using one bearing inner race as die, lube the axles and press them through, thus precision sizing them. (Or pull a long length through.) That or do a quick spin in a lathe with some abrasive paper or drawfile.
http://www.onlinemetals.com/merchant...192&top_cat=60 (Beware of specs - these seem pretty close for drawn rod.)
If the shaft is undersized, I might try some Loctite 620 Bearing Mount or 641 Bearing Fit.
Just a backyard mechanic's opinion, and not necessarily suitable for high speed, critical service.