I'm not going to speculate but, your car should idle with that carburetor. i have a .030" over 383, big valve 906 heads, 509 292 cam bumped 4 degrees, 383 torker intake, MP distributor, MSD 6AL Box and at present Holley 750 in my Dart.
it started out with a edelbrock 750 and we will not get into...