Oversize valves?
Intake and exhaust?
You would have to modify the cylinder head and have new valve seats installed.
It may not be possible or even worth while.
Interference of the valves with each other during overlap has to be checked.
The piston clearance with the valves must be compatible.
But the cylinder head would have to accommodate the larger valves.
You must always check the valve to valve guide fit on any engine that is taken apart for rebuilding.
The max allowable wobble of the valve in the guide must be checked.
I cannot imagine Cycle -X selling you oversize valves with out asking any questions.