Oversized valves: good or bad?

Think of an engine as a well-oiled sewing machine.Carb has to be correct for; compression and cam. Intake the same. Cam has to be degreed for what the rpm is. Then, exhaust has to be tuned. And we haven't talked about piston weight, balancing, dissy, timing, etc.
It all works together when correct. this is how national records are won.