Your serial number/VIN looks correct for an MGC, here's a quick and dirty breakdown from the information I have on the MGC:
G - indicates that it is a production MG
C - indicates model as an MGC
N - indicates car is a roadster, a D would indicate that it is a GT
1 - indicates that it is the first series (and in the case of the MGC, only series)
U - this one is a bit screwy as there are different interpretations. The most consistent seems to be LHD US Spec, but I have also seen it as an indicator for LHD in general as well for MGs.built in the last quarter of 1969 onward to the end of production, probably not though given your build number.
6980 - indicates it is #6980 of the production run of ~9K total so roughly 75% of the way through the run and therefore probably a 1969. IIRC the US Spec 1968 models did not have the amber and red reflectors on the front and rear wings, the 1969 US cars did so that could potentially serve as a model year indicator.
G - indicates Abingdon built
Hope this helps in your dealings with the powers that be.