Here in south central Alaska, after I have my "meat fish" for the year, I exclusively fish Kings on flys. I use an 9' 8 wt. with HD Sink Tip. Early season Kings in slightly off color water, respond well to large rabbit flys 4 to 6 inches long. Chartreuse, or purple, with a little crystal flash tied in at each side are my favorites; shorter flys for very clear water. I tie them with enough floatation in the body (foam or whatever you can come up with), so that with a short 25lb to 40 lb leader on a fast sinking line, the fly will drift at about eye level with the bottom hugguing Kings. Wrap the rabbit right over your chosen flotation. I use 2/0 to 4/0 Siwash hooks for these rigs. Another producer in clear water is a very large "Glo Bug" about the size of a quarter. tie in a little white marabou to simulate skein or sperm. Quarter cast either of these patterns upstream to get the fly at "depth" right in front of you. Strip only enough to keep the line tight, and strike like the blazes at any pause. Be sure of your nail knot at the line to leadr intersection. Re-tie as often as necessary. I lost my biggest king (estimated at around 60 lbs) right at the bank due to the line weakening at the nail knot. You can also "Mooch" these patterns down stream into deep holes, keep the fly moving down stream below you in one foot releases. Be sure you're on the bottom. The strikes with the mooching method are subtle, so don't be afraid to strike at any change in your drift.
Good Luck!
otter