I would recomend an 8wt rod a minimum of 9'6' I prefer rods that are over 10' it helps to keep the fly above the boat and me ( not to mention the other fellow in the boat)! Any quality fly reel that will hold a fly line and 150+yds. of backing will do nicely. All this is recomended for Coho, if you want to fish Kings then you really should consider a big club somewhere from 10wt to 12wt. This because you are going to need to get down with big heavy lines and weighted flys and still have striking power but you will have a lot more action ignoring the Kings and casting comfortably with the 8wt for Coho!!!
Its a worthy venture this ocean fishing for Coho good luck.