http://www.texasaircooled.com/catalog/Front-OUTER-Wheel-BALL-Bearing.html
These are the parts involved. I'm not sure how you'd assemble it without the ball retainer. Beyond that I've got a ball-joint front end that has the roller bearings. The earlier link-pin front end has the roller bearings.
But I've heard of people spending (thousands?) on machining the front wheels and brakes on a Bonneville racer. If this works, someone (then everyone) will be doing it.