Triumph Repair: 74 TR6 died and will not re-start, fuel starvation, fuel compression

Question
I was about a half mile from home and the engine suddenly died. I have ruled out fuel starvation and I am getting a spark. I have checked the timing, replaced the plugs, cleaned the carbs, fuses ok, checked for any loose connections. Everything looks good but it will not start. It just turns over and over and over. Any suggestions? I am completely baffled!

Answer
Fuel, compression, spark, timing.  It always boils down to one of those 4.  Sudden failure like you describe makes me say spark.  

Points or EI?  
Yellow Spark or Blue/White spark?
Spark at the plug, the cap/rotor or the coil?
Spark at all 6 cylinders?
Does it sounds like any of the cylinders are firing?

Pull the plugs and do a compression test as a sanity check.

Are you seeing fuel in the throat of the carb?
Are the plugs wet after trying to crank?
Does it smell like gas in the exhaust?