L4staero, aren't you running Eddies? If so who did your porting in OZ?
Ramms in Sydney have been recommended as well as John White Racing Engines in Brisbane.
My charger currently has a stock stroke 318, ported J's and a 243/251 @.050 solid, victor 340 intake and runs 112.8 mph in a poorly set up car.
Ive used eddys on stock stroke 318's and they work very well but think without porting they are a tad small for 400+ cubes with solid where they need to rev past 6k for peak power.
I think an intake change is a very good choice before pulling heads and cam. Im going to guess you will gain 2-3 mph on the 1/4.
Please keep us updated on your results