Edelbrock 500 cfm or Holley 390 cfm

Hey guys. Looking for a carb for my /6 project. Already have an Offy 4 bbl manifold, and just attached a newly-rebuilt head to my '68 Dart. Looking for an Edelbrock 500 cfm (preferably an AVS), or a Holley 8007 390 cfm.

Hope to hear back.