I that the standard '82 CB650 or is it a CB650C or CB650SC? I have an '82 CB650SC and my experience has been that parts can be difficult to find unless you have a local salvage yard to pick from. The CB650SC was unique in '81, '82 after that some changes were made. Most of the differences were in the frame chassis with only minor engine changes (if you can find a "minor" part it quickly becomes a major issue). I have been able to successfully pull engine and carb parts from '81-'82 CB650 and CB650SC, as well as bits from other CB models from those years ('81 CB900 fork tube) Be sure to check parts list or drawings (bikebandit.com) to ensure that the parts you need are interchangeable and compatible with your bike.
Some other things to note: The seat section of the frame slants toward the rear and then comes back to straight/level after the shock mounts. If you are looking to make this into a cafe racer, and want the flat/straight lines you may have to get a little creative with a how you set up the seat pan. Also, the tank is kind of a funny shape for a cafe, I am restoring a flat bottom '76 CB750 tank. I would recommend sticking with the stock air box and exhaust until you have it running as it should, then you can think about these kind of mods. I put pods on straight away and was never able to get the engine to perform as it should even after trying multiple jets and mixture combinations...I am going back to the box (its hideous) and then working back.
In short, If you are looking for a bit more of a challenge when it comes to finding oem and after market parts this is a great bike. If you want to be able to pull from the many aftermarket parts dealers, find a bike that was more established i.e. not unique to only a couple of years.
Check out my photodumps
http://s1172.photobucket.com/albums/r570/tolchock5/82%20CB650SC%20july%20to%20current/?action=view¤t=P1040053.jpg#!oZZ1QQcurrentZZhttp%3A%2F%2Fs1172.photobucket.com%2Falbums%2Fr570%2Ftolchock5%2F82%2520CB650SC%2520july%2520to%2520current%2F%3Faction%3Dview%26current%3DIMG_0463.jpg
I would happy to give you any beta when it comes to this bike...I feel like I've made about every mistake possible on this build (my first), so I maybe able to help you avoid some headache.
Good luck