In my experience, most any weighted, small and flashy fly will work; the gear guys use all kinds of small lures, spinners and spoons and they all seem to work too. I posted a photo of my T-Krill pattern which has been one of my favorites, but probably only because I use it so often. I don't think shad are very selective. Finding the right location, getting the right depth and the right retrieve is more important than the fly pattern, IMHO.
I use the same basic pattern for just about all my shad flies except I do the best with a white marabou tail and red "thorax". Other color combinations include all yellow, all white, all pink. But the marabou tail, tinsel/chenille body and weighted eyes remain consistent.
Been just absolutely derbying fish in the lower C below Bonneville in my boat. It's fun, but seeing how many shad there are this year has me feeling that this can't be a sign of anything good since they're invasive and booming in numbers while everything else that belongs here is not doing great. Hopefully they're not out-competing all the herring, anchovies, sardines, etc. in the Pacific.
Bummer about the scenery, though. Sucks having this down the street.
I think the Shad and Stripers were both brought over at the same time, from the Cooper River in SC if I'm not mistaken. Both shad and stripers have kind of established in the same rivers, but the stripers kind of stop at the Columbia (yes, there's stripers in the Columbia/Willamette in small numbers). I think shad are often found as far north as the Skagit. But the main rivers they're all in are the Sacramento River (and tribs), Umpqua, and Columbia. They're scattered around in other systems in smaller numbers.