I had similar problems initially, but then switched to "Mr Gasket" product which is asbestos sandwiched onto a very fine stainless steel wire mesh. Very strong. Here is the key though that could apply to most all gaskets, . . . I ground down the area on the gasket between the actual ports to be very thin. This way when you tighten the bolts, you are not trying to compress an entire foot and a half of gasket material. You are only compressing the material that actually surrounds the ports.
You can all thank me later
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