Guys: I was ask to report what I found with the bushing sizing.
First I made a set of the sizing pins. Worked ok, but took 3 passes.
Got in the sizing balls I ordered. I took a gear that I could push the bushing in by hand. Made one pass with a .6825 ball. Bore came out looking like a mirror, measured .6815. The pin is .677 = .0035 clearance. I then tried to remove bushing. Could not move it by hand with by 1 ton arbor press, could move with my hyd press. But remember went it by hand, and there was NO Loctite used. I think I am liking this way of sizing bushing. One pass and done.
I will try and post some pics when I get time. Thoughts? Dan

Dan, thanks for your report. I will keep this in mind for future builds.

Do you pass the ball through dry? How much oversize was the hole in the gear? If you pick up two more in which the bushings will pass through by hand and in one the hole is 0.001 bigger, and the other 0.001 smaller, than the one you just tried, what would you expect would be the result? To maintain the 0.0035 clearance across a range of different bore sizes, I would expect you would need a variety of balls.

Just did 2 sets of gears. These were ones that the bushing was tight in the gear. All came out to the same .0035 clearance.
I was trying the loose bushing because I am finding more and more gears with loose bushings. ( looks like bushing not set with enough clearance). I was looking to see if I could save them. I know they make new gears, but you tell my customers they have to buy new gears at $300.00 a set. "It is just a Model T, the old ones will not work?"
As far as how big can the hole be? That would a judgment call. If you can stand at the other end of shop and ring the hole with a bushing like a horseshoe, I would say no good. But if you have too push it with a little trouble and use Loctite, I say good to go.
Yes, Balls go in dry. Dan.

Kind of a neat application for ball sizing. Any concerns that the mirror finish would decrease the surface tension, allowing the oil to simply slip through the bushing rather than hang around and lubricate?

Thank you for the report, Dan. Dave in Bellingham, WA

Where do you get the sizing balls.

I got mine from Precision Balls. com I do not want to hear any laughing, Ok go ahead and laugh, I did not name them that.