340 X Head Value

I would not be concerned with that flash rust at all. A little phosphoric acid (ospho) will clean those right up. Im going to put a higher value on them than you guys. A set of X cores will be $300-$400 on average. With the price of machine work these days I would guess around $600 for the machine work. At the end of the day it will cost about a grand to do a set of heads.