This is what I do day in and day out for a living.

How much performance do you want? You can throw a cam in it and the valve springs, etc. and drive it until the internals go....which, remember, with ANY cam you are stressing the engine more as well as the transmission. At your mileage, since you have to open the motor to swap the cam anyway, I would go ahead and replace your big ticket items. Upgrade the heads, port and polish everything, go for titanium valve springs, use ARP parts for all your buttoning up pieces. Then you do not have to worry about blowing anything up. Also make sure your fuel system is capable of providing enough gas to the motor. I would upgrade there as well, but to what depends on what cam.

Now, you wanna get crazy, you can get a built 454, drop it in, slap two twins on it and crap your pants every time you mash the gas. But that requires transmission changes and A LOT more $$$$.

In short, what can you do to it? Anything you want as long as your wallet allows. Just make sure you get a DYNO. TUNE. Not a canned SCT tune, but get a professional to DYNO TUNE your truck. That's where the power is really made because we can dial everything in to work together and maximize performance and efficiency. I get a lot of guys in that did a cam "with my bud and some beers in my driveway" and they drive it in untuned wondering "why is it so rough", "my check engine light is on", "my gas mileage is terrible", "it feels slower than it did before". You gotta let the computer know what you changed so it can take advantage of it.

Do not strain the engine by putting on turbocharger or supercharger, unless you rebuild the engine completely.