I just did an engine overhaul after a spun rod bearing. I bought an overhaul kit from Partsology.com.....gaskets, rings, bearings & pistons. Plus a new pushrod. Then took it, the dismantled block, crank, cam, head & associated parts to American Machine in Spokane. They did all the machining, short block & head assembly for about $800.
The engine has about 3k miles on it & runs great so far.
A couple issues that occur to me that you may have. There are 2 different 4.0 liter heads. Apparently one is prone to cracking & not easily repaired. Plus if your engine was overheated, both the head & block may need to be machined flat again.
There is a tool to disassemble the fuel lines.
