Bingo! That is the WMO engine base on the old old RACE perhaps 2000. Novarossi has changed their crank case twice since then. It has nothing to do with the P5. We ran one of those on club days 3 yrs ago. It worked ok compares to everyone's engine at the time. Then the rod split and broke the engine. At the price, it was not worth rebuilding it so it went into the bin.
The only common they have with the P5 is the plastic carb.