dynoed my 416
I don't believe the heads are aa problem. That is a smallish cam for a 4" engine. So I'd expect those numbers. You can tell by the flat peaks that it is not a max effort deal. Slip ina cam with 250°@.050 and that lift, even in flat tappet form, and those numbers will go up a bit, the torqu will peak close to the same, but it will not be as flat. For the cam you have, the 750 carb is fine, because it's almost done at 5800. But, you would have more power with a bigger carb. I spec 870 Avengers for my mild 408-422. I wouldnt play with rockers. Get a better cam, or run it. I think it will be a blast to drive.