Sornora pass is pretty steep with gradients of 8% in many parts and a few as steep as 26%, and is the second highest pass in the Sierras at over 9000 feet.
If you are coming from Walnut Creek, you may find Carson pass, though a little longer, actually a faster drive. The easiest way is to continue on 88, after Stockton, until you get near Gardenerville, NV, then cut across to 395 via Centerville Lane. You can also turn right at the Markleeville junction and follow CA 89 to 395, near Topaz Lake. That involves a pretty steep climb up and over Monitor pass and a thrilling 9% average gradient east of the summit.
You can also take CA 4 over Ebbetts Pass, but the down hill part east of the summit is heavily traveled by bicyclists and motorcyclists and is pretty steep until you get to Silver Creek Campground. And it still puts you out where the most direct route is CA 89 over Monitor Pass and its 9% descent.