Unless you just want to tear the entire engine apart and start all over from the shortblock up, just go for more intake manifold and more carbureation.
Like I said, two 4v Holleys with vacuum secondaries and progressive mechanical linkage LIKE the Ford 427 medium riser set up is where you want to be.
That setup uses two 715cfm carbs where as the low riser uses two 652 carbs.
The beauty of the set up is that the engine will only take what it can use with the vacuum secondary carbs as opposed to the Carter/Edelbrock/AFB set up which has mechanical secondaries and open whether or not the engine needs it.
You can port out the Price 2x4 manifold to flow more with not much trouble but I would invest with a professional porter with a flow bench to get it as close to right as you can get.
You are already running a lot of cam to begin with. I don't know at what lift those heads develop maximum flow but your duration is ABOUT as much as you want for a strictly street car unless you want to idle at 1,200rpm or more?
It all depends on how much more work you want to put into this and what you are willing to put up with to max out the engine.
You really won't know that until you go to much. The engine will loose it's civility really fast and you will drastically shorten the engine life exponentially.
You asked for opinions. That's mine.
