I promised to inform some interested guys what I finally found out regarding the blown gaskets at Columbus. Seems like I've passed the 7/10 century birthday, projects move more slowly.
The engine is back together with the new block, but not in the car yet. I used a straightedge and feeler gauges on the head in the suspect area. I put a .001 strip under the straightedge and could easily pull it out. Tried a .002, couldn't pull it out. Didn't want to take any chances at this point, so I took the head to my machinist. When I picked it up, he told me that he found the whole area between the front two upper head bolts, like it was caved in. Then he told me he only had to take .003 off the head to true it up. I would think a composition gasket could handle that. I couldn't easily pull the .001 strip from under the straightedge on the block, but the pitted area remains that didn't clean up when it was decked. I sure hope that was my problem. I'll put the block in storage for a later project. I'm sure it would be fine on a non-supercharged engine. It's already decked, bored .030, deeper main bolts, 1/2" head bolts, groove behind the center main.
I've gone back to the Best gaskets on this build, will see next season if it's fixed.
John - "The Hoosier Hurricane"