Hi, Mathieu
I think you MUST disasemble your engine, Mr Ruschman 's thoughts are the right way, xxxx$ spent in your head , i should want to be sure it will work.
The good process is start FROM ZERO , clean every parts, and rebuild .
in French : te fais pas chier , Mathieu, démontes tout, nettoies, et remontes !! I can help you if you want !