Where do I find a 1979 Kawasaki Mojave ATV Engine parts diagram?

My husband's friend tore apart our 1979 kawasaki mojave atv engine apart and then let it sit out in the rain, he then told us it was rusted and we should give it to him! Needless to say we went, picked it up, and are now trying to put it back together. However, we know nothing about atv engines. Can anyone tell me how to find a picture of the parts or something to help us figure out how to put the engine back together so we can use it again?