New intake manifold worth it?

I'd spend some money on fitting some bigger tires on that hummer first.Until you get traction, you're kinda defeating the purpose of that big cam anyway. Or did you just put it in there for the awesome sounding idle.
My engine combo is much like yours. I have a 68 FormulaS clone, stick car.My car was "dangerous",until I put 295s on her. Then it was too quick(IMO) for street. I swapped out the 292/509, for a 223*fast-rate. That was a sweet cam, but when it dropped 2 lobes, I replaced it with a 232* fast-rate. Now it's just right,for me. And it doesn't send me into 360s at every chance it gets anymore.
BTW, I got a kick out of the comment regarding fuel mileage.