That particular flight pack has a receiver that is "shift selectable", so it will work with your JR transmitter.

All of the commonly found servos in the US will work in all of the common receviers. Some companies like Futaba put non-standard plugs on their servos, but you can cut the little tab off with a knife and shave the corners off and use it anyway. (I do this all the time).

Spaceclam,
While I don't doubt you saw what you saw in your test, everything I've read and know about how FM and PCM actually works tells me your test was "lucky", and that while it might have worked for you for that moment, telling people it works all the time would be misleading, as it doesn't. I've seen almost the exact same test, PCM TX and RX on and doing a range test, then an FM TX is turned on to see what happens, the the PCM immedatly went in to failsafe.

(PCM failsafe vs the good (non-futaba) PPM receivers in a "dirty" envrionment is an open debate, one I won't go in to here, other than to say that I won't fly PCM personally. And a couple of guys at my field just tossed all their PCM went back to PPM recently. But I know others swear by their PCM gear, so ymmv.)