This whole concept of "outer race" is incorrect. There are only two parts to a journal bearing, the journal and the bearing. In the case of a cam bearing the bearing is called a bearing insert or shell.

Machining down the OD of the bearing insert is impossible. Period.

JohnRR is right, fix the cam bores in the block.

This is not a big problem, and seems to affect certain engine families more than others. B/RB engines are one of the families that is affected. Deal with it.

R.