From the looks of the pictures on the Ebay ad it looks like this engine has had quite a bit of use.
I've built/rebuilt alot of engines and maybe the costs are too high... but wouldn't a hone job , rings, and a couple bearings do it wonders?
The problem with used engines is that many times you wind up putting enough money in parts where you could have just purchased a new engine instead. And even with all the new parts in it, it's still not going to run like a new engine.
Ken