Autopsy complete. Results

If it's all the intakes on one side, that's not a fluke. I would very carefully check the stem heights on it. Even a straightedge would help accross all the valve tips. If the intakes are higher, that could be enough to put too much preload on those lifters. Also, the head gasket is about .020 thinner than the factory would have used, so you're loosing some there too. I'm beginning to think you may need shorter pushrods, I cant rtecall if you had adjustable valvetrain or not tho... You will, in any case, want to set the lifter preload without the intake on when it goes back together, and make sure every lifter has what it should (between .010 and .030").
The thick sludge is a mix of iron particles (run a magnet thru it...), moly from the cam and assembly lube, the silicone that may have been over-used, and the EOS...lol. It's all had time to settle out, so it's all there. That would be why they say drain the break in oil and change the filter immediately after the cam break in, while it's all still hot and all that crud is suspended in the oil. When you drain it, it has a strange sheen and color to it too.