5.9 magnum?

^Yup, these engines are tanks, they aren't like old ones; they run forever. Unless abused, they commonly have zero bore wear, or real wear of any kind, well into the 200k or more miles. I'd check the bearings, including thrust, give it a gasket job and let it rip.

I'll have to agree! My 5.2 has 160k miles and looked like a new engine inside. I pulled the heads off intending to do a full rebuild. The cylinders still had the original cross-hatching. After much research and consideration, I lapped the valves and buckled it back up. If it ain't broke, don't try fixin' it!