741 Housing, 742 ring and pinion..... can it be done?

trying to fit a fatter shaft into a small hole-not easy. the 741 inner race has an o.d. of 3.0", and the 742 and 489 inner race o.d. = 3.5". I searched and did not find a race/bearing with a 3.0" o.d. and 1.750" or 1.875" i.d. a custom batch of bearings could be made, what would the minimum quantity and price be? I wonder if anyone has looked into this? can the inner race 3.0" bore of the 741 case be machined out to 3.5"? I think there are enough 742 and 489 cases around so forget about it.