no.  exhaust gaskets are meant to be crushed when torqued down.  plus a set of fel-pro gaskets is probably under $10 for a 350 at any auto parts store. 

Is this an automotive 350 or for a boat?

If automotive, have the manifolds surfaced and run em with no gaskets. It'll last forever like that, gaskets suck.


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Skip the gaskets and just use high temp silicone.  Much better than gaskets.