It’s unlikely there would be big gains by doing nothing other than changing the valve sizes.

Even with a 2.02 valve they can have turbulence issues unless someone has profiled the short side radius.
If they are only marginally hanging on in the high lifts now, a bigger valve will probably just induce turbulence(or have it occur at a lower lift).

As with just about everything flow related....... there’s only one way to know the answers to your questions....... about your heads.