360 magnum valve train

The truck avenger is a really nice carb.

Is your air gap intake an edelbrock or is it the Pro products deal?

If you're feeling adventurous, you could buy a timing chain with adjustment and advance the cam 2*. That should help with low end a bit.

Before you go spending money modding the stock heads, I'd buy a set of Iron Rams from Hughes (or EQ heads from someone else-whatever). They're relatively inexpensive and will make significant power and torque over your stock castings (and won't crack like the stock stuff either).

The best part is that they make a casting with the LA style bolt pattern, or you can have them dual drilled for LA style intake manifolds. you could then install an intake that was a little better suited to your truck. I've got an air gap and its awesome, but its definitely softer down low than something like a Weiand Stealth, plus cold start manners will be better with a non-air gap intake.