Cam and Stall Convertor
I know you asked about cam and converter, but I think you also need a lot more gear. 3.91s are not near enough gear for a drag only car. What's your RPM through the lights on the top end?
You want that little motor getting into it's power range ASAP and getting you going down the strip.
Way back in the early '70s I was running 4.89s in my '69 Dart on the street behind a stout 340 and a reverse-manual shift 727. Radical for the street? Yep, but it sure could get you home from the store before the ice cream melted.