Compression numbers and oil pressure are about all I worry about in the block itself. If those are good, I keep it and work with the peripherals. If all the rockers are popping up and down without undue noise, then I consider the head to be good. These old engines are practically invincible. It's the 20 year old sensors, timing chain, etc that I focus on. You'd be amazed how many headaches a simple vacuum leak or bad ground can cause.
Let's start with the basics. What seems to be the trouble with the truck?