Speedmaster heads are on and running.....

Yep. You gained. Good job. Teaches mis matched is mis matched no matter how bitchin ya think itll be.
You have a great low buck/rpm combo and killed it with quite simply... the wrong head.

Lightly ported is about as far as that cam and combo will go before they're left behind. Open the valve a true .480 or so, rpm range 2500- 6000 and the speedblasters will do their job.
I'd like to see the 360 head back on, lighty ported . I wanna see the max potential realized. Thanks for sharing.