In my youth, when I used to ride and maintain my own motorcycles, a warped head was dealt with by bringing it to an engineering workshop to have it skimmed. I can’t remember whether or not the valves had to be removed beforehand, although it might not be a bad idea to replace the valves and valve-guides while the head is off anyway. Skimming and rebuilding will cost a fraction of the price of a new/recon unit.
The membership association for owners of Dufour Yachts