Are they poured babbet bearings or inserts?
If they are babbet bearings, it can be fixed, but you have to find someone that still does that kind of work near you.
If they are inserts, a new set of main bearings is a small price to pay for piece of mind. There is no way to repair it, so if it were me, I'd replace it.
There is one thing a scratch in a bearing is good at, and that is collecting debris. And a little debris can do a lot of damage quick.
