1972 340 demon

That's a cool car. I think you're going to have to part it (dig up a 318 someplace and sell the 340 on its own, rallys instead of Welds, that kind of thing) to get that kind of money.

Do those welds have rubber valve stems?

Why would you want to part such a nice mopar? Someone will pick it up and have a very nice 340 72 demon. Good luck with the sale.