Best bang for the buck?

I have to agree with Rusty Rat Rod I absolutely detest getting people to spend money. Although you started out with looking at Edelbrock heads and I can't recommend those with what's available now on the market for a budget like your title says. you have a lot of stuff for a fast car combination but just kind of need the finishing touches to take you to the next level. Overcoming the low compression is helped by a thinner head gasket and a smaller chamber in your head. Anything short of that would be putting in different Pistons to come up higher and make a smaller area to squish the gas and air..
Tuning is great but were you wanting to go is going to require horsepower..