What cam to use in 340

Apparently you're no familiar with the early race W2 heads (iron). There are small block strokers out there with over 400 cid using ported W2s running in the 10's. I'm sure they're all running solid rollers. I don't think I'd tell them they wasted their money on iron heads. As you mentioned...It's all about how much air you can flow through the engine.

you are talking about a rare exception to the rule and as you mentioned, those heads were ported, not stock, therefore, the same rule applies with one minor alteration, roller cams are a waste of money on iron heads UNLESS they are heavily ported W2's.