I did not re-torque the heads after startup. There was a couple of years between engine build and starting it, and in that time I don't recall that ever being mentioned. Still, that's on me

My friend that owns the performance engine shop ran a straight edge over the block, and using a feeler gauge, he could not get the .0020 between the block and the edge, but with the .0015 he could make some progress (with a little effort) but not much. He felt the block was okay.

I believe the root cause of all this was the head. At some point in the engine's history, there was a shallow crack in the cylinder head in the area between #6 and #8. It was repaired, my friend thought they used 'pins' to fill the slight gap. It ran nearly the whole width of the head surface between the two cylinders. The head was then resurfaced to remove any excess metal in the repaired area. But they didn't get it all or as good as they could have. Running a finger over the area directly between the two cylinders you ciould still feel very slight unevenness in the repaired area. You guys know the rest.

Not sure if this was a contributing factor, but some of the cooling passage were blocked in the area of #8. This head buildup may have added more stress on the head and the gasket. I didn't drive the car that much so I never had the cooling system flushed in the approximately 15K miles the engine had on it.

I have some spare engines, heads, etc. to hopefully get me out of this. Some are 241, some are 271. I understand the heads of the 271 will fit on the 241 block. Will the larger capacity of the 271 heads be worth it?

I want to thank all who replied. I appreciate your input.