Hot running problem: sequential diagnosis

[Bill Newman]

My Z900A4 has recently started to run very rough once it gets hot - sounds like it's on one or two cylinders, will not tick over, struggles to restart while hot, only gets going again after 10 minute cool down. The plugs (all four) are very sooty at this point. Starts from cold on the button, warms up fine and is OK after 7-10 miles. But after 25+ miles I have this rough running problem.
The bike was completely restored in 2012 and has covered 9000 miles since. I rebuilt the top end last winter .5mm rebore, new pistons, rings, valves, guides,genuine Kawasaki gasket set including stem seals and have covered about 1200 miles since that rebuild.
Having pondered this problem and relying on my instincts that a hot running problem is usually associated with ignition, my thinking is to diagnose as follows:
1. Check the valve clearances in case anything has settled/bedded in a little quicker than I might have expected (this is easy to do and involves a cam cover gasket);
2. Replace the condensers those fitted are 9000 miles/5 years old (and were Kawasaki NOS). The points are fine: no pitting etc;
3. Replace the coils in case of breaking down when hot;
4. Strip carbs and investigate chokes/pilots
Anything I have missed/should include in this sequence?

[Pigford]

Bill,

Sounds like an electrical breakdown - most likely a duff coil, or maybe a condenser even?

[Julian_Boolean]

I've got a pair of coils off my J you can have.

[Robw]

Bill, fit a dyna s kit to bypass all the ignition problems and I have a set of green dyna coils you can borrow if they are the correct ones.
Rob