Help ID or Info 73 Commando

My father-in-law and I have several Commandos. About 15 years ago he bought one locally from an estate with no information. When we got it home, got it running and cleaned up, it got pushed into a corner of the garage basically because we were unfamiliar with the body parts, the significance of them, and didn't really want to mess with the bike because we tend to want to modify/"improve" everything. Also, the bike is overall in great condition including paint, appearing very original. Anyway, I posted some pictures at picturetrail hoping someone can tell me something about it. Dunstall? Factory? Someone's idea of cool? Bike does pull hard. Thanks, Chad

http://www.picturetrail.com/sfx/album/view/24362950

Its an 850 Mk2, late '73 build.
Body kit is Norton Production Racer (NPR) but may be replica.
Rear Sets are NPR as best as I can make out, but missing the large one piece mounting plate, instead attached to the stock Z plates.
Mufflers are Dunstall Decibel.
Great looking bike and good luck with it.

I'm never at the right estate sales. Ugh.

Is it for sale?