"Built up" Mopar 318 on Craigslist. Upselling at its finest.

I think your tearing into this guy without any real evidence of what you portray.
He did say there .020 Hyper slugs inside a seasoned line bored & square decked block. That does not suggest to me a engine that just had parts thrown at it with a cam shoved in.

And he does clearly state that it needs a rebuild.