I'd get the surface emery smooth by whatever means you deem necessary, not worrying too much about streaks. Buffing wheels would work fine but if you're concerned about the mass of one bogging your grinder down one of these puts down a decent footprint:
http://www.caswellplating.com/buffs/tapered.html
Once it's emery smooth take out the streaks and finish it up with one of these:
http://www.caswellplating.com/buffs/flball.html
You've got 6 inches of surface area coverage to work with on one of those, which oughtta permit you to strafe your grinder in a straight line back and forth across the part while having enough overhang to avoid streaking. The only stipulation on this Flitz Ball is that it's only liquid polish friendly, so you'll either need to use some of the Flitz brand polish or you could possibly get away with using some of Caswell's Liquid White Rouge.