I worked for Rubber City Vintage Cycle, a vintage bike shop in Akron for a couple years. They were dabbling in this sort of stuff but decided in the end to stick with parting bikes out.
I also have a cb350 motor coming together this summer, and I wish I knew someone who did engine work/machine work because I'll need someone to lap my valves and a couple other odds and ends I don't feel like screwing up.
Even though the shop doesn't do service work anymore, if you need parts they have tons of stuff for 350s. Some is on ebay, a lot more is still in the shop. ebay seller id is RCVC. If it's cheaper than paying shipping you can pick it up from the shop.