Engine messed up. Replace or rebuild?

[Dclassen]

Well my 72 K5 has been in the shop all week after running weird. I believe it was rebuilt less than 30k miles ago. Long story short I just talked to the guy at the shop and he said he popped open the head covers and there was no ****ing oil in it. Said was out of alignment and I would need to replace camshaft or replace the whole thing and they were still looking at it. Keep in mind these guys get 5 star raving reviews for good work and honesty. Honestly I just wanna go cry right now. How would this have happened? I just got the oil changed about a month ago. I'd be SOL trying to sell it so I'm thinking a new motor would be better. I couldn't part with this truck, my dad drove it for 15 years. Any ideas would help, I barely know anything mechanically.