If you are 18 or less as "just a stupid kid" seems to imply, and/or your budget is as severely limited as you seem to imply, then you only have one good course of action. The best improvement you can do is replace the head, if that is in fact the problem. Having been a kid with a stupid quick Ranger, and it was only a 2.8L, I can definitely recommend keeping the truck slow. Going fast at that age will really hurt your wallet.
If you are serious about building a fast truck, have enough of a budget to get it going, and know what you are getting yourself into, then by all means build away. I'm actually going to recommend taking the long way around to making it go fast. Get it running good, then start with brake and suspension upgrades. No point in making a lot of power and going fast if you can't use it or stop it. Being quick is more fun that being fast anyway. There are laws limiting how fast you can go, there are none that limit how quick you can accelerate or maneuver.
If it really is a cracked head on this motor then obviously you'll have to compare options, and see if it's better to replace a head or swap an engine. The 4.0L or V8 swaps can be fun, but I will never recommend a V8 swap if there's a chance that it will take the Chevy into a Ford route. I'm a diehard Ford in a Ford guy (same applies to other brands as well), but if you're going to go the over done engine swap route at least make it a Hemi or something interesting.
EDIT: Sorry for the long reply. Mine are always long and they get worse as I get tireder.