Hitchcocks in the UK are the source of all things old Royal Enfield - mostly new stock though, andf the postage is a bit savage. There are other UK suppliers, on ebay too if you watch and are not in a hurry.
Lotta new stuff coming out of India too, some will suit older Enfields and the prices are lowish, but climbing. Only a few of the suppliers are good quality though. Someone in Newcastle NSW has older Bullet stuff, changed hands a few times, should be easy enough to track down.
For the paint match, you need to find someone with an Enfield for a paint sample. The paint colour is polychromatic silvergrey.
Scan from the brochure, for 1955.
http://www.hitchcocksmotorcycles.com/pictures/partsbooks/1955_350CC_BULLET.jpgWhile some use metallic paint to match this, poly paints are actually pre-metallic paint era. The paint has extremely fine aluminium powder in it, not metal flakes, and has a silver sheen to it that metalflake doesn't. Modern "pearl' paint is similar in character, if you can find the right shade (VW or Audi ?).
You probably need to figure out the year of your bike too, since the features change with the year. That curved muffler only covered a few years, is that your bike ?
Hopethishelps, Havefun.