I would find a bearing house and have them check the availability of sealed bearings by dimension. It would be easy to go with a smaller inner diameter because space would not be a concern. The question will be ...is there room in the overall diameter to accomidate the larger axle hole? Then you'll need to have some spacers turned to center the assembly. Get a harley bearing and a triumph bearing and take a width measurement at the hub, then go to a place that sells specialized bearings.
