Joules, the way to determine that would be to overlay the intake manifold gaskets for the heads in question.
I'll attach the picture I posed before of the A3 gasket, the 2v iron gasket and the 351w gaskets here. A picture is worth a thousand words, or more.
I do not have the gaskets for the Chi heads. Do they have their own unique gaskets?
I would think that the bolt pattern on the intakes would be the same as all C family heads.
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