Don't ream them.....way to easy to grind them down too much or not get the hole straight.
The best way is the qtip trick Brandon from team paridm came up with. Take a qtip, pull a LITTLE of the swab off.....then put it in your dremel, dip it in some mother's billet polish(available at any schucks), and then polish the bushing at medium speed until dark black. Use one qtip per bushing. Then polish the shafts of the armature using the polish and a rag, just put the arm in your dremel. I do the pinion shaft side first. Works great and you will have SMOOTH bushings.