I agree with rcmodel - not much. Practice and experience matters more than parts.
The stock GI sights...well let's just say they don't jump out at me and I have to hunt for them sometimes.
Unless you are Canadian and talking about some variant not available to us US residents, your pre-ban Norinco would have come not with GI sights, but with tall three-dot sights from the factory. There isn't a whole lot out there that is going to be much better, really. They are solid, the front sight is basically welded on (it will be heck to change it - they were silver-soldered on and are notorious for destroying carbide cutters if you try to dovetail the front). For the cost and hassles on changing the standard Norinco sights, I would learn to use them - they are pretty good as these things go.
I carried this Norinco in the early '90s. The only real exterior change I made to it to make it more carry friendly was a hammer and hi-ride beavertail. I changed the trigger and MSH only for better fit to my hand and shooting style, not as a "carry" modification (I much prefer 1911 to 1911a1 style).
I also added a FLGR as it noticeably improved the feel of the gun - the recoils was more linear and smoother. The gun was reliable either way, but it feels better with an FLGR.
Later on I changed the fire control components to Caspian parts and tuned them, but that was more because I had parts and time on my hand and not because it was necessary for reliability. I have tried extended safeties, mag releases, etc., and those things are for the range. For carry, stock works fine and often better (snags less).
It is hard to make out the white three-dot sights, but they are on there and that is what is standard on a US market Norinco. This gun now has walnut double-diamond grips (just didn't seem right using the take-offs from my Series 70!) and a commander hammer, but this is pretty much how it's been for 15 years or more: