if its possible to restore to flying condition a Spitfire that has been buried in salt water/sand for 40 years
It isn't. BUT! If you have the data plate and the drawings, it is legal to build a new aircraft around the data plate and put it into the air as "Restored". What they are really digging for in Burma is a couple of dozen original data plates and the Griffon engine blocks and data plates to go with them.