Facing a tough call on my old diesel: rebuild from the ground up or just swap it out?

I've got this 1990s diesel truck with over 300k miles, and the engine is starting to knock. On one hand, I'm thinking about a full rebuild. I've done it before on smaller engines, and it feels good to bring something back to life. Plus, parts are cheap if I shop around. But last time, I didn't catch a worn camshaft and had to tear it down again after 500 miles. On the other hand, a friend swears by dropping in a remanufactured long block. He says it's plug and play, with a warranty, and he was back on the road in a weekend. But that costs three times what a rebuild kit does, and I'm not made of money. I'm stuck between saving cash and learning more versus spending big for peace of mind. What's your take, folks? Have you been in this spot before?