Chain & Sprocket Upgrade

I would like to upgrade my chain and sprockets on my 79 sr650.It still has the originals. Whats the best setup?

If by "upgrading" you mean replacing them with new, Z1 Enterprises has all of it at really good prices.

As far as the best setup, it depends on what you're looking for:
Going one tooth larger on the front sprocket (OR one tooth smaller on the rear sprocket) will slightly lower the RPM's at freeway speeds, but might make your bike seem a little sluggish when taking off from a dead stop.
Going one tooth smaller on the front sprocket (OR one tooth larger on the rear sprocket) will give your bike slightly more "Umph!" from a dead stop, but the top speed will suffer slightly by a couple of MPH.

I run a 16/42 set up. 20 years ago I went 1 tooth smaller on the front and the bike was way quicker! But 1st gear wound up so fast it hard to ride, so a couple months ago I went back to stock and now is a must more civilized ride and 500rpm's lower on the freeway. Later I might even drop another 500rpm's...