My research would suggest closer to 300 FC 217's made.
All Holden's old records (that weren't thrown out) went to the Adelaide library. There does not appear to be anything there which indicates how many of each model were made or what colours etc, so my research analyses what vehicles are still remaining and by recording ID plate details and chassis numbers I can statistically analyse what was originally made. Of course there is an error margin that has to be factored in but better than no info at all.
Little known fact is that the FC 217 was discontinued either late 1958 or very early 1959. No GMH correspondence found as yet to indicate a date. So this makes the model a very short run. There are many more FE 217's around than FC 217's
With very little Holden records available it is not possible to know how many staff sedans were built by the factory. I'm betting that the information would exist somewhere in the army records though!
Here are the facts as I know them - two are known to exist, I restored one of them and another is currently for sale needing restoration. I don't know of any that were wrecked.
There is a FC staff sedan in the army museum in Wodonga but it is a 215 model.
I would expect that there were more than two made, but how many is just speculation.
Ken