Yeh the welding is the easy part but welding that close to valve seat can create issues down the line.
If I was to weld it I would strip it a bare casting then grind out the crack heat the casting throughout and weld it up.
It would then probably require machining to allow the valve seats to be pressed in with the correct interference.
All stuff that can be done of course but not financially viable for this build or head with that value.
I'm sure I can find some, I know I have some Mexican 043s which are good but have the smaller valves so id prefer to use some 113s which I believe I have a good set