My niece was recently looking to buy her first vintage bike and of course asked me to help [my brother not too happy!]
She found a CB350 for sale and I met her there, the bike was not in very good cond and the guy was just flipping it and really knew very little about it. I test rode it and was not impressed, it was a real dog.
Just so happened that a buddy of mine had one so we went over to his house and test rode his. All original and only 3500 miles. Ran better but still not impressive, get the 450 for sure.
She bought this for $1900...