Push mower blowing smoke and fouling spark plug. Bad ring or maybe just bad gasket??

I was given a walk behind MTD Yardman. It starts with a new plug and has run intermittently since I picked it up. I finally got tired of killing myself every time I mowed my lawn (1+ acre) and decided to tear into it and see if it's worth repairing. All of the decals have worn off and I didn't find a serial # on the engine. The guy who gave it to me said he tipped it on its' side to sharpen the blade. The piston and valve heads show a lot of carbon build up and oil definitely got into the cylinder. The cylinder itself was smooth. Judging by the photos, what's the best advice for finishing up this project without spending more than a new mower would cost me? Also, I managed to break off one of the bolt heads that holds on the valve cover. Am I screwed?

Thanks for any help is greatly appreciated.

Chris

you can buy a new engine from harbor freight for 100 dollars.

First thing is to make sure oil is not overfull and air filter is not soaked with oil from tipping. After that you could do a compression check but it would hardly be worth it. If you found it needs rings You'd have to buy rings, a gasket set and you never know what else then still have to do something about that broken bolt. The worst part is if everything goes right and it came out perfect you'd still have a crappy mtd someone gave away! If the mower is otherwise in good shape reply #1 is probably the best bet.