I've caught many kings using an Orvis Battenkill 8/9 disc on a 9' 9 weight rod. It was not the perfect big game reel but it did the job from the late 80's until 2005. These are good quality reels and sell on auction usually under 100. they are by no means a heavy drag reel but will work with some help from your free hand palming the rim. If I were buying another I would get a 9/10 size not the smaller 8/9.
Since 2005 I have been using a mix of reels for salmon. I picked up 2 Orvis Odyssey reels, a #3 and a #IV, they are both great reels for big game. The original Vortex reel that Orvis sold are also very good salmon reels. Some of these hold their value very well because they were made in America but sometimes you can pick one up under 200. I realize that 200 is not cheap but the reels are of good quality.
A good drag is very smart when fishing for king salmon but they can be reeled in using less than state of the art drags. The fish below is not a king but a good size silver caught using a 7'9" Orvis Far & Fine 5 weight with an Orvis CFO IV reel with a click and pawl drag.
Not a king by any stretch of the imagination but I post the photo to say that if you can handle a fish like that on a CFO then you will land some kings on whatever you use.
2 things I will advise you on are; be sure to buy a big reel so you can have at least 150 yards of backing on it. And.......... make the backing heavy, heavier than the leader by at least 10 pounds and be sure you have a solid connection between that back line and the fly line.
I'll send that link now,
I'll PM you a link to a reel that works great for salmon. If you bought it there would be no need to upgrade in the future.