Head gasket question

On my 367, I have run Q as tight as .028 with alloy heads, no contact/no problem. That was a firecracker out the dual 3" pipes at 11.3Scr and 180psi.
But on the inspection teardown, at the end of the summer, I found those .028 fire-rings migrating into the valley.
So I re-engineered for the FelPro .039s, and Q is now .034 and those FPs are taking 180psi just fine.
This is a cast crank 360 with bushed 340 rods and KB107 hypers under OOTB Eddies. Skirt clearance is generous at least 2.5thou. I'd like to be more accurate but assembly was in year 2000, and I just don't recall anymore. I remember taking it apart and opening it up because the engine would tighten up every time I shut it off. So I had the machine shop add a thou, to whatever it was, and I increased the top gap. which solved it. And bonus the engine ran cooler. But it rattled just a lil on cold mornings for just a few seconds. So then, afterwards I increased the minimum running temp to a tic over 200,lol, no problem.