From the paint, the style of gas tank, the headlight and the side covers, I'm thinking a '68/69. Actually, they didn't really make '69s as a separate year model, they just sold the leftover/later # '68s. You won't find parts fiche for a 69 specifically. It may say a different year on the title but back then, many states titled it whatever year it originally sold in. So if it sat for a few years at the dealer, it may say it's a 70 or 71. Definitely not older than a 69 though from what I see. If the frame/engine says cb350-1xxxxxx, it is definitely a '68/69 model. Each year after that went up 1 number for the 1st digit in the VIN. i.e. CB350-2xxxxxx, 3xxxxxxx etc.
Depending on where you live and what kind of shape it's in and what it needs to get it where you want it to be, show bike or ratty or daily rider, $600 may be a bit much or just right for a starting price. No more than that though unless it's cherry. We have 2 CL350's, which is the scrambler version of this bike. Parts are everywhere and these bikes were some of the biggest production bikes made by Honda so not rare or anything. Selling price should reflect this. Some parts are almost impossible to track down though.
Make no mistake, you will probably need to put quit a bit of $$ into it and spend some serious time setting it up so it runs right. They are very touchy carbs and many people end up putting on other ones that are easier to deal with. Having said that, Paulages set up our '73 for us but it took many ultrasonic cleanings, much messing around, much resetting, many pissed moments and scratching of heads to get it running really well. Paul has done 100's of these and still had a rough time until it finally fell into place. I'm not saying they aren't good bikes but they do take some serious dedication to get them running smoothly.
For carb rebuild, we just went with the o-ring sets from Honda for $11 as I recall, no new jets since the bike has around 5k miles, tire sizes are hard to find for these, so many go with Avon Roadriders 90/90-front and 100/90 rear. The air filters are pretty expensive, at $35 each, depending where you go, over $42 each. The cables usually need replacing and if the front brake one is toast, good luck finding a new one. They no longer exist. They have a electrical wire connected in the middle of it on a switch for the rear light. The years after '68/69have it separate and the right handlebar pod is different. When you do find one, it will run around $80-100 for the correct one.
Front and rear drum brakes.
Only 1 fuse on the whole bike.
Some parts are good for all years but not all obviously. Good luck.