Not sure what my problem is!!!!!!!!

Hey Guys, My problem is that my car surges forward when I'm stopped and the car is running. Its not real bad but definately noticable. I adjusted the idleing down which helped but can't go any futher or it stalls in gear. I also noticed that when I'm on the open road my car acts as though it should have another gear or something. At 50 or 60 MPH it sounds like the tranny is screaming. I don't know if these are related but figured I'd mention it. A little info. on the car is 70' Dart Swinger: 440 motor with a 650 DP Holley carb.: 727 trans. with shift kit and stock convertor: 3:55 suregrip rearend. I had a 2800 stall speed convertor but it made the car feel like the tranny was slipping on pull outs. Any and all help would be greatly appreciated, please though if your not sure don't send me on wild goose chase. I've been trying to track these problems down all summer so now its time to ask someone who knows. Thanks Dave