headers?

[gregfull]

I'm new to this site and need some help. I'm doing a ground up on a 72 burb, I've planted a Ram Jet 502 between the rails and need some suggestions on headers or cast iron manifolds. The deal is that I need an O2 bung in the header or manifold. Does anyone know of a header that will fit the 72 and have the O2 bung for the sensor?

thanks.