Head Swap HP questions

Hey,
I have a fresh 468 in my 90 454 SS. 1.50 dome TRW Forged pistons, Edelbrock performer plus cam, .500 lift, 270 dur, 115 lobe seperation. It has worked peanut port heads on it, 119 CC, opened up ports and gasket matched. I have a set of 3993820 heads off a race motor that have the 2.19/1.88 valves installed, 113 chambers, port/polish, really nice heads. Heads were on a 12:1 race motor, I still have shortblock F/S!

Question: How much HP can I expect from the head swap?

Question: How much compression will I pick up from 119 CC to 113 CC, I still want it on pump gas. With old heads was 9:1ish.

I built this as my "work truck", and still use it as such, just a really nice work truck, lol. I could use more cam for power, but 10 MPG is low enough, not trying to build a race motor, still want the AC to work.
http://i411.photobucket.com/albums/p...g/DSC01369.jpg