I have a line on a 4 year old genuine gx120. The Guy is asking $60 and he said it runs. I have seen that mods like a cam and other things are not cheap for the 120 and they arnt that common. This concerns me because I want to mod it for more power. From what I see, it sounds like a great deal for an engine that could run forever. What do you guys think about this engine compared to a h.f. clone or a Briggs flatty?