"Short block" means the engine comes without heads, manifolds and other "stuff". It's also known as the "lower end" that you're trying to find.

Your choices are pretty much as already identified:

1) running junkyard engine (complete) - ~$500-1000
2) Japanese import - ~$1500 or so
3) remanufactured long or short block - $1000-2500 (crap shoot - particularly on the long block)
4) buy a junkyard core and rebuild it - core is $300-500 + $1500-2500 to rebuild (if you do most of the work yourself)
5) take your engine apart and see what can be salvaged - still, a minimum of $1500-2000, depending on what's done, who does the work and how many parts you need/want to replace.

Sometimes, it's better to buy another truck unless you're really attached to the one you have.

Frank