I've seen many quote a kind of ... rule of thumb phrase ... that is to be found on all the various boards
"You don't wanna use 302 combo parts on a 347"
The fact the combo is done at so early of an rpm kinda causes me to have the gut feeling that is what is happening here
I was kinda thinking those heads were a bit more able to flow more than entry level 302 heads such as AFR 165's and TFS TW's. I don't know but maybe something like AFR 185's.
If that is the case with those heads
You would look to the intake and cam ... seems to me
You could go to a better flowing intake
You could also port that track heat for more flow as well
You could also go with a cam that may be more suited
Again, just thinking out loud, but I somehow or the other think the cam just might be the weak link in your quest for more power.
If you were to do ... just one thing .............
I suspect the cam is where you would find the most gain as opposed to the intake ... again ... if those heads flow pretty good.
I look forward to seeing what you guys come up with
Grady