Why can't the machinist simply straighten the head? ie heat it and warp in back with a press? (it is a common thing to do with aluminum heads). If the head gets too low you may get weird running conditions, or you may have no problem at all. Sounds like these guys are just CYA'ing which is perfectly understandable. The problem is there are no guarantees with any repair that it will work, they usually do about 90+% of the time. Your call, fix it or forget it and buy something else.....which may have a whole new set of its own problems. Sorry I can't be much more help