If you are looking for a commuter bike that you'll use daily in the summer and care more about parts availability and any particular quirks that might not suite the bike for those purposes, then there might be some models you should avoid.
First, I'd not get a '69 - if you got one for what you are planning to pay, sell it at a profit and get another year.
I have a '75 K. I think the middle of the model run is about where I'd look for a commuter.