Every valve that has contacted a piston should be replaced regardless, and provided there are no cracked liners, then a top end overhaul is all that is required.
Mat Price has the exhaust valves
HERE
Inlet valves
HERE
I think looking at the contact patches on the valve heads, that you will be fine on the bottom end, and a bit of rework to the heads, then refitting would be preferable to trying to source another engine and fitting a complete lump.
Brian