I don't know what kind of strip to make down deep that will excite chinook but I'm fairly certain that a very slow twitched retrieve
My success in this area has been with t6 full sink lines around kelp. When stripping I like to change up the rhythm. With long slow pulls and short 6" pulls in rapid sucsession. Quite often the problem I find is getting the fly to the target species and not intercepted by Sea Bass, Cabazon or Coho. Although Coho is generally a good thing.
I know several anglers in my area that will be giving "Chinook on the fly" alot of effort this year.
Cheers N I