Don't metal head gaskets require a perfect finish on both the block and head to seal correctly? I had my block out so I could have the deck shaved and the shop still would not recommend going to a metal head gasket. Seemed that over the years water/coollant eats away at ports so that even a good shave will not it get right.
before block prep
after block shave
Unless you going to remove the engine block grind the block deck to perfection - i'd go with a composite gasket. It will be much easier and last 20 years