I just went through this with my 98 half ton. I debated on the 383 stroker, 6.0, 5.3 and rebuilding the 5.7 L31. I really wanted to go with the 383 stroker, but cost wise, the 383 would cost over 6 grand for a long block, and building it doesn't really shave off much. I wasn't able to find a 6.0 with low-ish mileage, so I decided to go with the rebuild of the L31. The 6.0 is cool, but any LS swap will really nickle and dime you. You have to start with the computer swap, then buy the A/C and Alternator relocating brackets, motor mount adapters, fuel line connectors, exhaust modification. Its not a simple drop in and go swap. That being said, if you know what you are doing, do your homework, it can be done. I kind of wish I had been more patient and found a 6.0, but, oh well.
I upgraded my cam to the Comp Cams 08-409-8. The other option was 08-500-8, but it requires different rockers and lifters to achieve the required lift. The 08-409-8 will fit with stock lifters, and it makes pretty awesome power.
You can really wake up an L31 with a few upgrades and modifications. First off, 0411 ECM. I'm replacing my black box ECM next month with the 0411. Next is a custom tune. I have a Black Bear tune. I really like it, and Justin did a great job! They are a little slow to respond, which is frustrating. The 0411 will give you more tuner options. Adjusting the TQ management, lockup, and dialing in your tune to your truck really makes a difference. Next is the cats. I deleted mine because theft here in SW Washington is getting pretty stupid. I will reinstall some high flow cats once they figure out how to curb this issue. Removing the cats opened up the performance a little bit. The engine pulls a little harder. Electric Fans will take some drag off your engine especially driving around town, traffic and hot temps with the A/C running. If you haven't done it yet, upgrade the spider injector to the new version. Doing all these mods will make your truck a little more zippy and powerful.
The 383 is worth the money if you have it to spend, and if you plan on keeping the truck for a long time. A fresh L31 compared to a tired L31 is a pretty great upgrade. You will really notice it when climbing hills. My engine pulls better and easier. I don't have a race truck, but it feels like the truck is not working as hard as it used to with the old tired engine.