I've gotten several "lightly used" engines that looked similar or worse than the engine pictured above. I personally use a regimen of acetone soaking for 30-60mins, blow out with air, rinse with acetone again, blow off with air, and add oil. At this point if the bearings feel pretty smooth, I'll run it and check the bearings after a few tanks of fuel. If not butter smooth (or rather - if they make any noise whatsoever, I replace the bearings.