A couple of thoughts on this scenario:
1) If the slide, barrel and frame are all Norinco, it's not a "parts gun" but rather a "modified Norinco."
2) The other parts are then worth a premium or discount to the base price of a good used Norinco ($400 to $450) based on whether you find them desirable mods, or you really don't want them and would have preferred the original configuration.
I have a Norinco pretty much stock except I installed a Videcki long trigger, Caspian sear/disconnector, Colt commander hammer and a high-ride Caspian beavertail. I put in a flat rubber-coated Pachmary MSH for comfort and grip. The gun has a superb trigger now and shoots great. I'd maybe take $650 for it as it would take that much to recreate the gun or find one that shoots remotely as nicely. I probably couldn't get offered over $450 for it, so I'm not selling it.
If you wonder how well the parts were installed, then check them out. Examine the fit and finish, look at how they are wearing, and run the gun through a pre-purchase safety inspection. Figure out what the gun is worth to you as it sits.