Carb jetting/adjustment on 79 KZ400

I went out riding yesterday for about 2 hours to feel out my new to me KZ. The bike never missed a beat until the top two gears above 5-6k rpm. If I tried to go WOT it would stumble and cut out until I backed off and slowed down. It also seems to hang revs slightly. I need to be able to cruise 55-65mph. The bike is stock, carbs were rebuilt by the previous owner. Next week I plan to install a 2-1 exhaust and pod filters and wasn't sure what jetting and adjustments I need to get the old girl to wake up a bit more. It seems like it's starving for fuel in upper rpms. Thanks for any input!

Pics of plugs?
Steve

You'll have to take the carbs off and see what the PO did. "I rebuilt the carbs" is usually an indicator of future problems.
Pod away but I would get it running well first using the stock air box and exhaust. If you can't do that, adding pods and a different exhaust will only compound the issues.

Valve adjustment and timing before going to carbs.
Steve

I've never messed with a points ignition system...this should be fun!

Hold on to that airbox. You may want to put it back on the bike. Ed