You might be better off with a stock 440 intake with that converter. It has been 44 years since I had my 69 , but this what I remember. Stock short block stock heads and stock cam 69 charger with a Holley 3310 750 , 2 inch open headers with collectors . It had a stock converter, 3.91 gears and 28 inch tall slicks and went a best of 13.06 at 103 mph with the stock intake. Try shifting at 5500 and work from there.
I also remember getting my but kicked for the first 200 feet on the street by a 318 Duster with headers when I added a hydraulic crane cam with 284/290(?) duration to that same setup.