Well, how fast do you want to go?
Let's be honest, if you want a hot rod, a truck platform can be, but isn't really the best route to go. Of course, that mainly depends on whether or not you want your truck to still be a "truck"...
Me personally, I have accepted the fact that my 4x4 Ram is never going to be "fast" but that doesn't mean that I can't make it relatively quick. I've been talking with a certain individual down in Texas and we'll see how quick a mostly factory-spec 5.9 Magnum can be...
I regularly use my truck as a truck and performance-wise, I will be happy once the "death flash" is finally gone since that (and the plenum leak) are the primary performance killers of these engines.
But if you really want to go fast, then as Dodge Dude said, you gotta pay to play. Me, I'm not a forced induction guy, so I'd say build a 91 burning 408 stroker. A handy 400 horsepower while still being easy to work on/with.
And as others have said, dump the spacer. Spacers help with more complete atomization of gasoline in carbureted applications within the manifold but do absolutely nothing in our fuel-injected engines where the fuel is added to the incoming air right at the intake port. Certain spacers are said to create a nifty "whooshing" sound under throttle, so if that's your thing then it's no harm.
