You might think I'm crazy but I've always used stock manifold gaskets with my headers and have never had any leaks. A oldtimer auto mechanic told me this trick so I tried it and it works great.
Mullinax, you're not crazy. I use stock gaskets as well and have never had a leak. I just open 'em up to the port size and they're only about $10-$11 dollars at NAPA. I know they have the air injection ports, but you can't see it once they're installed. You can cut a slot in the bottom of the stud holes with a pair of dikes and just slide them in with the headers just pulled back too. Avoids the whole anti-freeze mess. Here's a pic with the part #: