l bought Buschurs's Ported/coated stock exhaust manifold and bought o2 housing, what gaskets do I need or can I use stock? Thanks. (I work late and have not been able to call them, no responce from my e-mails to them)

 

There are usually two elements to porting a cast iron part. The first is to match any passages with the gasket. When I ported my 10.5 hotside there was a fairly dramatic mismatch between the gasket opening and the passages or ports. So the first step is to grind the passages to match the stock gasket. So, the gasket is the template. Therefore, the stock gasket will be fine and it should not require any modification. Ideally, both passages on both sides of a gasket match the gasket opening exactly. Otherwise, the flow will cause turbulence when it hits the mismatched "ledge" and reduce the net flow.
BTW, the second step is to increase flow by removing casting flashing or flaws.

 

Thanks.