So what reamer do you plan to use?
I was chatting to a friend today who is a very competent engineer (but not a cyclist). He wasn't sure how important precise alignment would be in a journal bearing for such an application, but said that, if it were him, he'd look to ream the bushes first, then fit them to the spindle, and only then fit them to the frame, as this should help with alignment.
He also said, interestingly, that the wear tends to be to the steel, because the softer parts flex rather than wear.