the HS-65KB is about the top of the line for a analog servo as far as quality for the price. I installed them for my cyclic as they are fast very strong and no play at all in the gears. The HS-65MG (metal gears) have play in the gears as most metal gear servos do and are not that suitable for cyclic not that they arent a good servo but you don't want any play in the cyclic if you can avoid it. As for a tail servo they are not that good due to not being as fast as some of the compitition for the price.
They will fit just fine with a little hand work on the frame and the stock esky mounts as they are a little deeper then the stock servos. You will also need to change all to ball links to fit them properly and poss bend a control horn with a heat gun on the front if you are running a 28mm motor such as a Esky 3800.
Hitec HS-55 has issues and always has on Heli applications and the HS-50 is very small, light and fast and designed for 1/2 airplanes NOT Helis such as the King ll.