Here's our California as it sits now.
I had a pair of Michelin Country Rock 26x1.75 tires not being used so I put them on for now. They are a great improvement over the knobbies but I have some Compass Rat Trap Pass 26x2+ tires in the mail.
I came across a Truvativ Elita 9/10 speed tandem crankset with bottom brackets for a great price and was able to install it on the California. The frame's curved chainstays allow the narrower road crankset to clear without issues. The new crankset and bottom brackets dropped 1.2lbs from the bike, mostly from replacing the heavy steel bottom brackets.
More photos and details on the install here:
http://davidp.org/micargi-california-crank-upgrade/
New wheels are next - rims and hubs in hand, spokes on the way.