Anyone running a set of RHS heads with factory 340 exhaust manifolds ? I know there were issues with running them on Magnum heads

I'm running early 340 manifolds on factory Magnum heads. Some guys have had trouble with a bump on the Magnum heads that would prevent the manifold from bolting down flush.

To me, the bigger problem is the floor of the Magnum exhaust port is raised significantly to improve on the flow. This leaves only about 1/8" of common gasket sealing surface between the LA and Mag ports. Remflex gaskets solved my leaks.

Is this your motor ?

No, but that is a great shot that shows the mismatch at the bottom of the exhaust ports.

I made some sheet metal adapters, outside dimensions traced off an LA port, inside dimensions traced off the Magnum port. I'm not sure if they helped or not. The driver side sealed properly with my adapters and parts store gasket, but the passenger side needed a Remflex gasket to seal.