Back to the Z finally. There wasn't any problem with the borrowed carbs. While the tank was removed, I removed the petcock to find the filter screen had a film of light rust on it. The tank was flushed again to be sure no rust remained.
My carbs looked good but at this point I decided to replace the o-rings with viton instead of the ones that came in the kits.
Carbs were installed and the bike started immediately and sounded good. A short ride and a plug check showed a nice but dark brown pattern. For now, the air box will be replaced with some air filter pods. This may affect performance so will wait until I have a few more miles on it to see if jetting needs changed.
The last thing to pop up was when the starter solenoid wouldn't engage the starter. My old test meter didn't show the voltage drop between the motor and frame. The new test meter however showed 12.57 volts at the solenoid but only 10.32 volts at the starter. Time to retire the old meter. Obviously I didn't clean all the powder coating off the frame before I installed the motor. I added a ground wire from the battery to the motor and problem solved.