Do not buy any gasket parts from Napa of the other generic auto parts stores. Go to a speed shop and order yourself a Felpro set of gaskets. These are steel reinforced and they'll last a lot longer and you'll sleep better at night.
As for the heat palte, it's easy enough to make one out Aluminum or call Tom Langdon @Stovebolt Engine Co.
Do not run a single exhaust when you have a split manifold. The faster you get fuel and air through your motor, the better. Do not restrict the exhaust.
I use Corvette Chambered mufflers that baffle the exhaust at idle, but give you straight thru performance when you give it the gas.
