Has the deck of the block ever been checked for flatness? How are the cooling passages in the block where they meet the head?

Not familiar with this engine, but had a mitsu do the same thing- the block was warped at the head & the cooling passages were all mushroomed out at the head mating surface. Had to have a custom head gasket made, dropped the thermostat from a *195 to a 180 & ran the ignition slightly retarded- unit's been fine since (about 4 years running).