I'd use the 920 heads. That is what was on the D/Dart. They are a closed chamber and have a swirl port design. As far as the D4B goes, there were two of them. One has the Chrysler part number (CHRY2836139) cast into it. That might be the one you have to use.

I should swap cam, intake and carb and run my D/Dart in a stock class. Would that be legal even though it has an LO23 vin?