Gotcha. That adds up with what you said about keeping it running under acceleration. That leaves the float, needle, and idle mixture circuit. If those pass muster, it shouldn't be the fuel system at fault.
Out of curiosity, how's the distributor rotor? Generally a silly question, but worth asking about - just in case the centering tab has stripped itself (bizarre, but I've had this happen on a Ford Duraspark rotor).