No gravel roads on either 74 or 79. 74, just out of the Palm Springs area will take you immediately be up in the mountains, up to 8,000 feet - not unlike your home area riding, but some fairly spectacular views. Some good twisties, but some crazy drivers on it sometimes though. Just take care on the hairpins. It's only 70 or so miles between major towns, so if you gas up in the Palm Desert area you'll be fine. It's really a great ride, and hopefully it'll be sunny. If you do it in March be prepared for some chilly weather, possibly even some snow. Yeah, not exactly what you expect when you think Southern California.
What if the Hokey-Pokey really is what it's all about?