Some lovely pictures being put up in this thread!
If it was my NC and i didnt want to keep it stock then, id start with the suspension mods, fork internals and a decent aftermarket shock. As for twin stacks the Yamamoto spec A is a lovely looking system, or you have got the moriwaki, mercury, tyga, ganador/JHA, MHP cant remember any other ones off the top of my head but they are all going to be a nightmare to get hold of bar the tyga one, well worth it just for the rarity of them. Setup the carbs to match and together with the suspension mods it will improve the bike no end!
Plenty of other little mods you can do to improve it but the trouble is deciding where to stop, im trying to keep the mods to mine quite subtle other than the exhaust but its tempting to go down the road of never ending upgrades and changes.
Whatever you decide to do keep us posted, its allways interesting to see what everybody else is doing with thier bikes.