there is a reason OHV engines can't perform OHC engines, mass. With OHV engines you need pushrods, which add mass to the valve train, these aren't needed in OHC engines. Generally to get more performance out of a given displacement engine, rpms are increased. When rpms are increased with OHV engines, you run into problems controlling the valves because you have a much larger mechanical system, which requires larger springs, pushrods also flex. All of this ends up mattering in a big way. F1 engines have overhead cams for specifically this reason.