I traded my perfectly good '07 Tundra for this '87 K10, and it broke down right away. We’re in it for the journey, though. Trying to keep costs under $6k.
The only limits are your imagination and budget.
An LS swap could be awesome, but it’s pricey to install.
A basic 350 crate motor costs around $2k.
You could also try your luck with a used one from CL/FBM, starting at $350.
It looks like you’re running a manual transmission. Adding 5th gear and overdrive would make it more street-friendly.
The 5.3L LM7 and 4L60 are widely available, usually ranging from $500 to $1500 depending on their condition. There’s also a lot of support available for swaps involving these components.
Wow, she looks both impressive and fierce! Enjoy whatever swap you choose to do!
Given that it has 1/2-ton running gear, I’d recommend sourcing a complete 5.3L/4L60 setup from an '02-'04 half-ton Chevy and an NP241 transfer case from a late '90s truck.
Is the $6k budget for parts with you doing the work, or is it to have someone else do the repairs and return it fixed? Clarifying this will help provide better suggestions.