Heads, how much gain?

Absolutely buy aluminum heads! Even indy ez have gotten affordable and they do everything better than stock iron. Look at cutaway shots of heads compared to irons! No comparison! Why spend tons of money on iron heads adding bigger valves and hours upon hours of porting when you can have incredible flowing heads that weigh far less! In my experience as I have eddys on my 11 second street car and indy 440-1's on my race car go with aluminum! ! Remember horsepower always starts in the heads! When the budget allows I would also ditch the old heavy trw slugs for much lighter je or srp or Ross pistons!