H.i.n.....
Your saying he repainted over the H.I.N..(hull identification number)?....wow, that's not good. Try this. There is another number on the motor, the E.I.N. (engine indentification number). It will either be on the back side about the PTO flwheel or on the front top casing at the magneto.
We may be able to cross your engine size and find out what models where made that year to at least get you close!.......