Advice on buying junkyard engines?

If I have to put more than about $500 into it, I'll just take it to the scrap yard.
Yup. As a Ford Truck Enthusiasts Forum member, sounds familiar.

However, don't "junk it", because if'n you have any relatives or good friends somewhere up here where road salt is as common as apple pie, even with a bad engine a "solid, rust free" truck would be worth good money, and maybe you could list it/sell it up here.

Heck, I just paid $8k for a rust free, 30 year old F250 out in Portland, Oregon to replace my current, rotted-out '92, and I'll be flying out there sometime in the next 2-3 weeks to drive 'er back. Truck like that would go for $12-14k around here, but I'm gonna drive it, not flip it.

Jim