The sound he played on the Nord lead is different to the actual RMI sound on the track,you can actually hear him playing the sound over the top on a few of the recordings of the concerts,so its definetly overdubbed,I think you can hear it more prominent on the full Moscow concert as you can also hear him playing the Eminent strings over the top as well on the first pass
As for replicating it exact today....well it depends on if he recorded the settings at the time of the actual recording,or more still has those patch charts or info to this day,during the recent tour,the sounds weren't 100% accurate even on the actual RMI in comparison to the original recordings,but this could be down to the instability of the instruments,those types of synths even replicating the same settings can have differences in timbre,so 30 years on theres bound to be discrepancies.
The thing is you have to disgard any preconceptions of how it should sound compared to the original When replicating,analogs have many flaws that make them unique in ways digital replications can't compensate for and much of that is that the sounds can be different even in the same edited state