ECU Dilema

[Kudzu911]

Have a 84 Euro 911 3.2 the ECU was rebuilt sometime in it's past by ECU Specialites, there is now a custom chip residing in it. It's tits up, have Injector pulse and everything else but no spark. Resoldered the section still no joy. I have a US ECU same part # except for the last digits, car runs using that ECU, can I just swap the chip and be done or do I need to have the Euro ECU rebuilt again.

Thanks in advace