Best place to buy used engine

[Aanic]

I'm purchasing a replacement used engine in the next few weeks. What would the site recommend as a good place to purchase from?

I see a fair amount on Ebay, a couple used vendors, but looking for advice from the group as to what they have done in the past.

Edit* I also have a line on a used engine in a junkyard, but its been sitting since 2015. Worth looking at with 140k on it?