I am trying to decide whether to use '68 style HP exhaust manifolds or 1 3/4" headers on my 383 build. It's a mild build, XE 274 cam, KB 400s, Stealth heads, RPM intake etc

The reason I'm thinking of using manifolds is because I installed the 1.03" torsion bars on my B body and I'm not sure if headers will even clear.

I have no problem with using the manifolds but have a couple questions:

Is there any problem mating a cast iron manifold to the 440source heads? Specific gasket to use?

Is there really that much of a performance loss to go with HP manifolds over 1 3/4" headers? Enough to notice a difference?

Thanks