Have you raced this truck on the track at all? I think your conversion to crank HP is rather "happy". I have a hard time seeing that combo making that kind of power. I'd have it closer to 420-430. MPH and weight would tell you the truth.
IMO - the gearing is holding you more than anything else. The current power may not be a problem. To get more power from it means more rpm and less torque. You give up low end to get the peak numbers up with that short stroke. If the "need" is a more powerful sensation at or below the rpm range you cruise at now, put in a deeper gear. That's a lot of weight for 3.54s and a 383.
If you are dead set on the changes - replace the intake with an RPM, add a good spacer, and replace the cam with a solid lifter with another 40-45 degrees at .050 and .080-.100" lift. Then it will make the numbers, but really feel like a pig.
