340 X Head Value

Problem with the resto crowd is that they are willing to buy junk at high prices. My dad is one who does that. He bought a 340 that needed like all the cylinders sleeved. Okay, so I'm not afraid to buy a shot out 340 and sleeve it to go = .060 bore but this man wanted to sleeve it and go straight to a stock piston size. I asked him why and he said he wants it just like the factory made. I'm like, "Look, if you want factory type performance buy a 318 and put a cam and 4-barrel on it. It'll run like a factory 340."
Nope, it HAS to have those numbers that nobody can even see unless they are under the car with a flash light. It's lunacy. Guys like that drive up the prices on regular old shiite for little casting numbers.
Whether a resto-guy perceives a higher value or not you can take a set of J's (or a Z or an O head) and for the same amount of machine work and porting you can have the same head.
If you want more power you're going with aluminum. If you want no problems with alt. brackets you're going with any iron and building them accordingly. If you want the most out of iron you're probably looking for something other than an X because the dolts have priced those out of consideration.
It tickles me when I see my Dad find the X on an engine at a car show, "Oooh, this has X-heads!". I roll my eyes.

For the OP, put the highest price on them and within a span of a year you will have some dolt come around and gladly buy them for $1000 and spend another couple hundred having someone clean them up just to use them. Understand that you don't really have anything special as far as the hardware goes. The value is purely in nostalgia for guy who don't really comprehend performance and value. My 340 came with a Z and O head. You want to talk about "rare"? They could even be the 2.02 valves from the factory too, just like some J-heads.

X heads are like Air Jordan's. The black kids are kiling eachother over them but they don't make them better basketball players. Like Air Jordan's, X-heads are a status symbol and people will pay/kill for status, BUT, get your precious X-headed Mopar and my Z and O headed Mopar and we'll have a motor car race and the heads won't be the deciding factor.

If you want to be fair and honest I would go $500 - $700. It would be a fair price for buyer and seller, however, there are a lot of fools out there and you're not obligated to help them keep their money in their pocket.