Help with picking out a carb for 5.9 magnum

The factory engineers were not dumb. Some 360s used 85o cfm carbs [ TQs ].
The Holley would make an excellent door stop...
Use an Edel carb. If mileage & general use is planned, the 650 AVS2 would be best.
For greater higher rpm performance, the 750 AFB or 800 AVS would be great.