The secondary resistance on your coils sounds fine. Each type of 3 Ohm coil has a somewhat different secondary resistance. The Accel coils are much lower than the Dyna coils for some reason. As long as they are both the same...
Are you using a fuel filter? I would first check to ensure that the petcock is not clogged. A stock KZ900 (76) had two outlets I think but if you have a good quality single out petcock and split the line with a vacuum tee, it should be fine. If there is a fuel filter, change it out... they can sediment up quickly.
