That was the engine and pipe I started with in 1/8 scale about ten years ago! I've said for years that for a 'budget' engine, there is none that are better!

If it were me, I'd just buy a new one. Once they suck dirt, all of the wear and problems can't be seen with the naked eye normally. So spending the money to rebuild it might end up backfiring on you (no pun intended).

Just my opinion though....

Brad