596 head performance mods

Using .100+chevy valves is the way and if they install seats on both int/exh they will have the valves sitting high on the seats -good for wedge heads- and will get the valve stem height like stock= 1.920 =no geometry issues.
If you use the chevy valve springs they'll probably just cut the spring pads for heights of 1.75-1.80 etc.