Shennui 254 with Hubei 295D engine

I have a Sheeniu 254  4wd tractor with Hubei 295 2 cylinder 25 horsepower 1.5 litre engine. Just got it and need to do the head gasket. Does the fuel injection pump have oil in it that needs checking and filling? I seem toi have all the manuals, but I amcurious about the engine origins. I undestand it is a very common engine made by many companies in China for tractor,  marine and generator use. It it a copy of another manufacturer design? what are the major issues with the tractor? and the engine? Mine has a loader and a backhoe and seems fine except no brakes and headgasket needs repair.