Not sure about the chop chop in C-town, but please give Kantaro a try. It's a sushi place, really cosy and all. Located diagonally across from Renaissance Parc 55's side entrance. Contact info for Kantaro Sushi is:
124 Ellis.
San Francisco, California
Voice: +1 (415) 986-2339
Give them a call to see if they're still there. Last time i visited that joint was way back in 1998. Recommend the BBQ set for 4 if you've got a party with you.
BTW, pls take care when you're around that area at night. Downtown SF is no joke beyond 4pm.
At the same time, it'll be nice to take a walk down Pier 39, check out the Coit Tower, Twin Peaks etc. Weather now may not be fantastic for high altitude sights though. Expect brisk winds and lots of rain.
Take that 17-40 and give it a good workout man, and enjoy your stay in SF.