The P38 sprockets are very different. They contain very specific spoke (yes spoke) design which is used for the ign timing. I'm not sure if the shaft size went metric but I don't think it did. For an engine with a dizzy you could use it but the better option, normally at lower cost, is to get a double row adjustable (adjusting the cam timing) chain set. It isn't that the standard Morse chain is bad but the cam sprocket is a plastic and the teeth cause it to wear very slowly, loosening the chain and messing up the cam timing. Adjustment for the roller chains is a complex process of selecting different slots in the crank sprocket but you can just set it on the standard slot with no effort.