BTW, I have been assuming your grips are the smaller "Magna" style though after rereading nothing is mentioned.
The larger target style grips would not be numbered that late but could have been ordered special or could have been added later.
As for the price on "a 6" -2, practically NIB, with all contents (tools etc.), and diamond target stocks"
Diamond target stocks are getting pricey and will drive up the price about $100 to $150 depending on condition and type as there are several different styles some more desirable than others,
But generally in my neck of the woods the gun you described would be between $450 with Magnas up to as high as $650 dollars with Diamond target stocks and everything original.