I've used both the 5935 & 5949 Mr.Gasket setups here...this is between a factory '596 head and Hooker #5901 Competition headers.

Both work fine, but they are slightly different sized, #5949 is for a slightly smaller port...not sure how they would seal up your existing combo though...you really would have to match them up I suppose and simply try them.

Looking at the gasket you referenced, the wide open center section will never seal against a header flange, I would want an isolated exhaust port...so from that perspective, how much of the inner port wall between the 2 exhaust ports did you remove? Or is there enough there that you can use one of the 5935 or 5949 gaskets?