If your pistons are somewhat close to zero deck you probably won't be able to run anything other than the performer rpm head or the 440source head (when it comes out) and run your car on pump gas. The 75cc chamber on the victor/indy heads would jump your compression up too high.

My neighbor went from stock 906 heads on his 440 6pack coronet to out of the box performer rpms. He is running a similar cam to yours, he only has 3.55s though. Just a street car, so no time slip comparison, but huge seat of the pants difference. I wouldn't be surprised if they were worth 50hp.