The top picture is it burnt or just a little bit of oil dripping down?

As for replacing bearing you need to mic your crank first you might luck out and your crank is fine but burning through the bearing to me says that the bearings were replaced before and not properly installed or the main cap wasn't cleaned up. It would behoove you to check your cam bearings too.

If it were me I would fully tear the motor down replace your bearing and maybe get the crank polished depending on the damage. As much as it would cost to have it ground you might as well buy a replacement newer stronger cranks are getting very affordable now.