I pulled the heads off my merc 420hp with 90 hours. The crosshatch was still there, but every cylinder had spots about the size of a nickel that were polished shiney looking. They are all smooth with no burrs or scoring. Would you run it? I really don't want to disassemble the short block.

Why did you pull the heads? Are the spots on the intake or exhaust side of the block?

Pulled the heads because they were seeping down the side of the block. The fire rings were not compromised. The spots were on both intake and exhaust sides. Seems like they are from the piston skirts pressing the walls during compression and power strokes.

When you say they are on the sides are you saying sides as in front to rear or top to bottom as in ^ or < to > ?

Perpendicular to the piston pin.