This is all perfectly normal. JR radio gear does work in the opposite direction to Futaba.

Check that all the controls are operating in the correct sense. They will all need to be reversed. By the way, how much of the radio gear have you changed. You need to make sure that the transmitter and receiver match. If you are using a Futaba tranny then make sure you are using a Futaba receiver. There is no problem with plugging JR servos into the Futaba receiver though (or vice versa but you will have to cut the locating tab off the Futaba servo plug).

You definately need to get someone to fly it for you first. It will save you loads of heartache to let someone who knows what they are doing check the model over and trim it out for you. Don't be tempted to try it on your own. I don't want to scare you but if you have a go on your own it probably won't last long enough for you to trim it out. (you'll see what i mean when you have your first go!).

Best of luck and let us know how you get on.