Yep, the peanut ports are nothing more than low end grunt truck heads. They fall flat on their face at about 4000 rpm. Heads are out there. The older you can find the better. And don't be afraid of 396 heads. Those will actually be the better heads to have. 72 up passenger car heads will be better than the truck heads, but by 72 they had the NOx bumps in the heads for emissions. Also the older heads are more likely to be smaller combustion chambers giving you some fair or better compression. Careful how much you spend on the heads by the time you buy them, then put them in the machine shop to have all the work done that you might want. By the time you do all that, you could have almost bought a good set of Aluminum aftermarket heads ready to bolt on and really wake that motor up.