340 block 1969

Mos likely the block was professionally prepared elsewhere- look for other signs all the bolts bottom tapped? oil mods etc
If the copper is flattened out it will not hurt anything
If it ain't broke don't fix it check and see if all four corners are dead nuts on
I would check if using mls gaskets or gaskets with a fire ring larger than the o ring or which crosses the o ring
for high boost applications I used Bellevue washers as o rings
head could move around quite a bit and the spring in the washer compensated