Union Models

Wondering if you guys may be able to help. I treated my trusty YS63FZ-S to a new set of bearings and new piston ring, as it was down on power.

Ive noticed the inlet and exhaust valve seats leak, a gentle hiss is heard. I know about relapping the valve seats. Should both the inlet and exhaust valve be a totally leak free, or is slight bubbles blowing from the seat normal.?

With a new piston ring, would I need to run the engine in again, as if it were new.?

Thanks Mike.