The last thing you need to worry about with a senior is servo weight.

HS81's are simply not enough for the ailerons, although they should be OK for throttle. You would probably be able to use 81's for slow easy flying, which is really all you could do with the engine and airframe you have chosen, BUT you risk stripping them if the wind comes-up while you are flying, or even a hard bump in the car on the way to the field.

I have the ARF, not the kit. This plane is a blimp. You could add POUNDS of weight before it would be an issue, even with that engine.

Go get some standard servos for 15 bucks and scratch the $30 HS81's.

Enjoy the plane. It's the best trainer ever, IMHO.