[Dave in MN]

Model "B" engines can quickly become "money pits" as the more you do to them the more they seem to require.

It is difficult to give an assessment based on only a partial view of two of the 4 cylinders.
I would guess you are showing us the worst area of the block. If you still have close to 11.5" total block height, a light decking of the top, just enough, to provide a good surface for the gasket would be required. Don't try to eliminate all the pitting in the combustion chamber as it is not necessary. The bad pitting in the valve area could be worked around by installing oversize valves and with the light decking you should be good. The increased diameter seat cut would get you to good metal. If it were my block, I would use larger valves, keeping them set high, before risking cutting in hardened seats, or cutting deep for standard size valves.

I used this method on two "B" blocks with bad pitting as you show. They both are not high HP engines and are still in service.

To counter the previous experience, I also had a badly rusted "B" I rebuilt for myself. I decked both the top and manifold surfaces to fully clean it up. I also needed to install three helicoils adjacent to the decked manifold surface. (More lost metal!) It failed at about 15,000 miles. The removed metal from the manifold surface weakened the block, enough so that it cracked at two of the head bolt areas with helicoils into the adjacent water jacket openings. I should have left the manifold surface alone as the gasket would have sealed it. Lesson learned, the hard way about removing too much metal and about money pits!
Good Day!