Welcome to the Bay Area!
I live in Pleasanton, which is about a 45 minute drive east of San Francisco (a little longer if you want to ride your TW!). I would be happy to help you replace your chain and sprocket if you are able to get your bike to my place. I am busy this weekend with the Cow Mountain ride, but most weekends would work for me.
Let me know,
p.s. I believe that you and I swapped engines a few years ago, right?