Yeah sounds like a great idea, some stock mildly ported heads would be nie or take your sell them and jsut put some bigger valves in it. We would walso need to know what kind of pistons your running.

 

Yeah, the power does sound kinda low for the cubes you have.
I like my STS personally, and the turbo is easier to update later for more power. A supercharger can be limiting over the base kits other than pulleys.
Also agree to change to the #317 casting heads before boosting above 5 psi on anything.
Have fun, let us know how it turns out!