Pull the center carb off and use a fine cut mill file to see if the pump housing and the fuel bowl have high spots on them scope wrench
Been there done that more than once to fix them mystery leaks runaway wrench
Take your time and don't go hog wild on filing them tsk
Let us know what you find thumbs

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)