I would suggest a edelbrock victor jr or rpm air gap(the tall one). Both will give you a boost in top end power but i think the rpm air gap is a little better for such a heavy truck. On the street you might already have the best intake.
Rpm air gap and victor will be hard starting in cold weather. Dual plane is better for street use in truck unless your going to for max effort.
But that being said the rpm air gap and a 750 carb will wake it up in the top end. But could cost et if its heavy and looses torque down low. But with 3000 stall it may work out. Would need a clear dyno results to figure where its lacking without driving it around. What you got is probably good to 5500 rpm but you may have a lot left over if it turns to 6500 7000 rpm.
I use this to figure compression Normal felpro gaskets are .041 stroke 3.48 rod length 5.7 bore 4.0 or 4.030 for 30 over. Deck hight is .025 if un cut with stock pistons not rebuilder pistons. They may be further in the hole.