340 X Head Value

I would say add $400 onto cost of machine work and that would be the price. They get naysayers due to being iron, which causes zero grief with pulleys/brackets/linkages. Is there a better factory sb head?
Yes. Any of the smog era heads are as good as the X heads with 2.02 and 1.60 valves installed. Understand, I'm no naysayer. But the simple fact is, unless someone is looking for a factory correct set of early 340 heads, their value is simply not as much as people are led to believe. Now, had they been a factory closed chamber quench head with the big valves, things might be different. But take the valves out of the equation and they are just another smog era open chamber head. Just the same as a J head or any other letter head. And don't forget, some of the early J heads on 340s also came with the big valves. Now if he finds someone restoring an earlier 340 and they want the correct castings, he has them and they'll command a pretty good price. But the fact is, you can do the same with any of the other open chamber heads and in fact, the factory 360 "swirl port" 308 castings would leave the X heads behind in terms of flow and power if they were upgraded with the big valves. He needs to find the right buyer and they'll bring some money.