Stock heads/rotating assembly, hot cam/vlave springs- how far can you go?

I guess the question for me is whether or not the Eddy Airgap is worth spending the $300ish compared with the Mopar dual plane that I already have. I had been under the impression that the M2 manifold was nearly as good as the Edelbrock but please correct me if I'm wrong...

IMO it's worth getting the RPM airgap. I believe it's the best option. Even if it's "nearly as good" it's worth having the best on there. PLus there is the air gap as an advantage as well.