Slant 6 4 barrel carb

I am swithing my '73 dart sport slant 6 from a 2 barrel to a 4 barrel carb. Already have an offenhauser 4 bll intake manifold, looking to buy a used holley 390 and rebuild it. There are 2 different types available for me locally, one has vaccuum operated secondaries the other is mechanically operated secondaries. Any idea which one i need..or can either be used?

Thanks