If yer going to do anything, just polish the arm.....and then lube really well...
We don't polish or ream the bushings anymore....
Why? Reaming isn't something thats EASY....in fact, your 99% more likely to do it incorrectly than to do it right....and even if you do it correctly, I still don't think it does anything worth a crap....
Polishing the bushings would be better in my mind......but it has the fatal flaw, that the bushings are very very pourous, so you can never get all the polishing compound residue out of the bushing....
A properly broke in motor will have the bushings broken in by normal wear.....just make sure they are fully seated in the holes before running the motor the first time.....
As for results.....not a single of the stock titles or tqs in the signature below had the bushings reamed or polished....so if we can do it at a national race against some of the best in the world, I am pretty sure you will be just fine at your local club race or two day event.
Later EddieO