These make a good truck motor but will choke out at 4500 rpms and cannot really be modified well to make serious power according to "my" head expert.

Ask your machinist if he has some decent heads around. You may get surprised and pick some up for a reasonable price.

There are apparently many good heads around for the BBC. I'm just getting into this myself so I'm no talking head.

Here's a few numbers he thought were premo:

049, 702, 290, 781. I know there are more that will make good HP and torque. The 702s and the 781 are open and the others are closed. I'd stay away from the closed unless you are racing or can modify them to use with appropriate rods, crank, pistons, gaskets, and deck to stay as close as you can to pump gas unless you're racing or willing to live with additives and the like.

My questions are these for you. What are you putting it in, what are you going to do with it, and how much money are you going to spend to go how fast?

I want some good heads to flow to 6500 and make about 450-550 hp with a flat torque curve for a mild to mod street engine that is nomally aspirated with an aftermarket manifold like a performer. I would like to stay on premium gas only.

What heads to buy even if they need massaging, what bottom end, rod type, pistons, rings, and carb as well since I'm asking.