Nice looking bike. For parts, use bikebandit.com, z1 enterprises, and your local dealer will actually be able to get quite a bit for it. Stock and engine parts at least. Aftermarket cafe parts can be had a lot of places, but I can recommend Dime City Cycles, Roc City Cafe and Fast from the Past from my personal experiences.
Your choke issues may be related to the lower bars using the stock choke cable. You may be able to make it work sufficiently by pushing out the choke on the handlebar all the way, then operating it on the carb end.