You're on the right track, my boy.
J, yes it'll be running Nismo cams as part of the R1 package, so the idle will be a bit higher and lumpier. Don't ask me how I know this lol...
For those who don't know, the R1 engine package (without taking into account the rest of the Nismo goodies on r34nur's car) is an engine-out deal, and, depending on the donor car, is worth $30,000 at current exchange rates. 450ps of RB goodness - effectively a 2.6 litre version of the Z-tune motor. When I have spare time, I'll translate the parts list for the package. Very thorough.
J, I'll put you in touch with my GT-R guru, he has connections in Omori factory who might be able to give you some more history on your car.