Again beautiful car! The exhaust system and underhood air aren't helping you realize the numbers you'd see on a dyno. I'm surprised the converter is flashing higher than it did with the smaller heads. Those 2 changes would probably get you to where you want to be. But of course a roller and 4500 carb will pick it up. If you're not running an extended reach plug that might give you a couple numbers. There's always oxygenated fuel too.