I'll try to post a complete summary table when I get a chance (maybe in a more appropriate thread on the specific topic), but I am switching all my lighting over to LEDs this winter, and finding it cuts the existing load by about half. For stock, I get the roughly the same as those of you above: 140watt base load and 303 watt worst case (brakes, turn, turn indicator, neutral indicator, and cooling fan). With the LEDs I used, that drops to about 70watt base and 125watt worst case. I was purusing used ZZR alternators on ebay, as my bike already has some extra electrical (PIAA lights, another set of lights, etc), but looking at how much I've reduced with the lighting, I think I've got tons to spare.
FYI, it does appear they designed the C10 with some surplus capacity for anticipated accessory loads. I did the same calculation for my ZX600-C, which as a 20-amp rated stator (at 10,000RPM!!!!), for 280 watt total output (at 10,000RPM!!!). I wonder what it's doing at 5,000rpm cruising? Anyway, the stock loading is REALLY similar to the Connie; same headlight, running light, tail, turn, basically the same ignition and cooling fan, etc. For it, I get 138.5watt base, and 301.5watt worst case, which actually exceeds the stock output (at 10,000RPM!!!). I think this shows that the worst-case load is expected to exceed generating output, as you're not going to be sitting with turn signal on, brakes on, and fan running for very long, so you can dip into battery reserve at stoplights for a few minutes with no problem at all.
FWIW, the ZX600-C is also has accessory bullet leads (behind the right rear side cover, same location as the Connie), which are fed by a dedicated 10A always-on circuit, so they even anticipated some accessory use on it.