Im currently building a 1979 R65, however the engine is turning into a bit of a money pit, everything I look at is knackered, already put pistons and new rings etc, sourced some 2nd hand parts barrels etc but the cost goes up and up. There is a completely rebuilt 1983 R80 engine on ebay would this fit a 1979 R65 frame, it would also have the added benefit of some extra oomph, not sure if its complete with gearbox, but failing that would the R65 gear box fit this motor? Any advice welcome.