Don't do it. Novarossi engine should use novarossi plugs. Vice versa with OS engines. The button head and plugs made from novarossi and OS, they have different tapered ( different angle ).

P3 plugs are meant for off road. Thin wire element( hot ) ideal for short burst of high rpm. ex. Jumping.

P7, P8 plugs are meant for on road. Thicker wire ( cold ) ideal for long period of high rm. ex. long straight