Hi Sinned,

You have an M87 one of the batch produced on or around the 2nd December 1988 by Bill Smallwood in various calibres mostly in .243.
There is no entry for your specific number albeit I have, all up to and immediately after yours, so not sure what became of your specific rifle.

I can say, albeit it may look like a C3A1 and have all the ingredients like the McMillan stock etc, had it been one that came back to PH under the Canadianicon Contract of 26/11/87 it would have been returned with a G at the end of its number.
Sorry I can't be much more help on it.