You mentined that this is your first turbine project. The Nitro falcon is not designed for turbines. You have to do several modifications to fly it with turbine. Also the JJ engines don't have the best reputation. I understand that this is a low budget project to enter into turbines. But If you can't find wich are the better servos to fit this project, I recomend you to get all the help possible from an experience turbine pilot near you. Take all the extra precautions in the modifications of the plane to ensure safe flying. About your engine choice, I have a friend that was trying to start his for a long time. Well he finally did start the engine and was running great. Until the day he try to maiden his tango. Doing some taxi testings in the runway in the acceleration spool the engine just quit after reaching 1/2 to 3/4 throthle. A lot of work and still no running. His solution was very simple. He now put an old ram 500 and just got two succesfull fligth with no problems at all. I wish you the best luck in your project.

Rgs
Alejandro