I say go for it! Why? 1. It is a first year RD350 and it looks to be entirely original, no big dollars finding things. 2. Go slow, get all the good help you can and before you fire it up take it to someone who'll double check it all. 3. A friend had never had a motorcycle, although he built bicycles, bought a couple boxes of late 60's Honda CL350 parts and built a perfect runner & looker. He did it, you can too.
4. Its' an RD350! (full recuse/disclosure former RD owner/rider).