You can't put Chrysler heads on a Dodge block. You need Dodge hemi heads.
That said, the DeSoto is the least valuable of the early hemis due to the lack of performance parts available. There are still parts out there for the Dodge engines, and of course the Chrysler hemis. The Dodge is the smallest (physically) and lightest. In terms of desirability the 392 and 354 Chryslers are at the top followed by the 325 Dodge and 315 Dodge, then the 331 Chrysler.
I sold my 325 with fresh heads in October for $1,750.