I guess it depends on what you want to do, either 3D or scale flight. Either way those servos are probably overkill for a 50.
For a 50 size heli either scale or 3D flight I would go for servos with a torque number between 80 and 100 in-oz. If you want 3D look for the upper end of the spectrum (closer to 100) or scale, then closer to 80.
If you are going for 3D, then I would look for faster servos. Closer to 0.10 sec for scale flight, closer to 0.20 is ok.
The rest of the equipment seems to be ok. Although I don't remember anybody using that type of BEC as a regulator. Why don't you get a regulator like an Arizona or something similar?
[link]http://www.fromeco.org/Products/02FRARIZ-200/Default.aspx[/link]
Rafael