Wow, I haven't seen that before, is is the top of the fuel cap?
the starter looks Victa, but then again those starters were not exclusive, the plate on the top is for a decorative chrome cover.
I imagine a number of the parts were from other turners, while I'm not sure the engine model was used on that mower, the cowl,a nd quite possibly the engine seem very turner to me, so they may have been pulled from another turner.