People go both ways on P/C or paint. I guess it's a personal opinion. I did the powder coat (painter called it 'liquid black' and I did the crown parts and the bridge on the front mudguard in 'chrome' which turned out quite nice), it was cheaper than paint, and despite what some people say that you can't repair it, black paint will fill a crack/chip just fine and being black it's hard to see. Last time I did it myself with zinc chromate and black spray paint from a can. Didn't hold up to the gas and oil very good at all. If you powder coat, note that the engine mount points have to be masked from the powder coat, you can see in my frame picture. Old Britts has a large technical article on it. I did the gearbox mounts too, paint the masked areas with enamel after assembly, you can hardly see it. It is much easier to mask the areas with plastic oven proof stick on circles that the painter should have than to try to get it off later and putting all those nuts/bolts/washers on is a waste of time and money. My painter wouldn't let me put the hardware on after stripping because he would have to blast it clean again from the grease on the hardware and he came up with all sizes of plastic circles and sheets that can be cut to shape. I masked it after it was blasted and before the powder coat with the painter so you might want to talk to the painter about this before hand.
Up to you whether you want the S look or not, even if it's not how the bike was built. You can turn a Norton into any style bike with the right parts. The S exhaust is not very stable and the shields last maybe 5K miles until they start fracturing. I think the pipes are more prone to cracking and the dog leg bracket cracks too. The clearances on the S exhaust are pretty tight. Only real benefit is you never have to worry about the kick-start lever hitting anything.
I have a real long thread on my rebuild if you want to skim through it, search for '69 phoenix'.
I'd be glad to help with any of your questions, probably most of them will come down to your preference.
Dave
69S