I bought an engine that was subposivly running in the late eighties. Pulled the heads and found some recent but not bad rust, I'm guessing "flash rust." I was wondering if there was a solution that could take this out or if I could just use something like rubbing compound to remove it. I think it's in to good of shape to rebuild and want to start it up and check how it runs without scratching the cylinder walls up too much.

 

Mine was in the same condition from the sounds of it. I used steel wool and penetrating oil (PBlaster, WD40, diesel, etc)and scrubbed. You might want to lay a rag on top the piston just to keep wool shards out of the rings. I got the worst of it that way and let the rings finish up.