looking for the best lingcod jig fishing in southern california?

You should just get some weedless leadhead jigs and put a grub on the back. Lings mostly eat rockfish, sculpins, and other greenlings. Jigs will catch them, but you'd probably be better off with a swimbait or dead bait. They really love bullheads. If you just target the rockfish, you might just find yourself a ling that decides to latch on. As long as you don't lift its head out of the water, it'll stay on and you can net it. If you're targeting them from shore, go to the rockiest area you can find that's facing open ocean. As far as size goes, #4-4/0 hooks will work just fine. I'd pick something small enough for a rockfish to bite too, because that rockfish could catch you a ling.

Generally the color is not that important.

Buy several different colors especially orange or orange and white. Good fishing.

I've never used a flat fall jig for lingcod -- those are better for fish which are up off the bottom. But they would probably work fine. For lings, I like the solid heavy jigs like the Jax jigs, in 8 to 12 ounce sizes (depending on the water depth), made with a plain wire (not forged) treble hook. The jig will get to the the bottom faster than a flat fall. You bounce the thing along the bottom as the boat drifts over the reef. If you snag the bottom, you can pull hard enough to straighten the light wire hook and get your jig back (the hook is plenty strong enough to not straighten when you have a fish on).

I like orange or orange & white jigs, roughly the same colors as the little rockfish the lings eat, but actually I think the color doesn't matter that much.