If you want to get a good idea of what is possible to upgrade for a reasonable price/performance, take a look at this engine master episode. The cam they used is probably too much for a truck with a stock torque converter, but it might be okay.
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I have the same basic engine in my truck, and its weaknesses are old design low compression heads (that cannot be simply reworked to be much better), and a very mild flat tappet cam. The best upgrades are better flowing heads (Vortec or better) with 64cc chambers to bring the compression up, and conversion to a more aggressive (preferably a roller) cam. Using aluminum heads instead of Vortec iron heads works a little better overall, and a roller cam conversion gives you more flexibility in ramp rates, etc. However, iron Vortecs and an RV cam should help a lot.
Scoggins Dickey sells stock iron Vortec heads, and also has Vortec heads that are already prepped to handle more lift.
Bruce