Good advice has been given in the above posts. Regardless of the motor choice, you'll want to make sure that your transmission can handle the new motor.
The 350/383 motors will not be as fuel efficient or have as much top-end capacity as the newer LS motors (design differences). However, the 350/383 motors will have more low-end torque than the LS motors. Given that you're driving an OBS truck, which has a black-box computer limiter of 5800 RPMs, and assuming you're doing "truck stuff" with your truck, your needed power will be in the low-mid range RPM range. The 350/383 crate drop-in will certainly be easier than performing an LS-swap (lots more components have to be changed/replaced for compatibility). That said, an LS motor can cost less than the 383 from a motor-only cost standpoint (based on sourcing). The situation really all depends on what you're willing to deal with and what you're wanting from an end result standpoint.
I went the HT383E crate route because I wanted the low-mid torque and already had many component upgrades that I wanted to reuse.