Well I / we found the problem I took it to 3 mechanics before the last one took it on as a personal attack to his craft and would not give up!! and found that one hot lead from the computer to the start/run circuit was connected at the starter solenoid and the Lokar neutral safety switch was also connected to the same lug and was back feeding 12 volts directly to the + coil wire so when the distributor got above the suspect RPM all that voltage was apparently causing spark scatter or maybe the coils field was breaking down prematurely but when we removed this wire from the start/run circuit the miss/backfire went away!!!
Thanks everyone for your imput without it I would not have eliminated those things and the mechanic would have spent at least another 10 hr. starting from the begining to eliminate all the other things first.