It sounds like you really want to use that carb. It really isn't a good match for any other component on your engine.
What will happen with too big a carb, it will bog and lose low end torque. You will actually lose power. Plugging in the numbers, 383 CI x 5500 max rpm/ 3450=609.5 ideal CFM x .9 VE= 548 real needed CFMs
If you could get right cam (Magnum ish) , aftermarket intake, elec ignition, headers, your motor would scream. If you choose a couple wrong parts, it will be a turd.
$400 isnt much coin to really make a dent in a project. I would concentrate on following the factory route with electronic ignition, 4 bbl intake and a Magnum spec cam. You can trade that big carb off, here's a link to a possible option for you.
Factory Refurbished Street Demon 1900 625CFM 4bbl Carb
Good luck with your build!!