Your going to look at either buying a new pistol here and then swapping out your custom parts.
I have heard that slides are ok, but frames are not. I am not 100% on that though. I do know that frames are not allowed in. At the very least I would take out any custom part you put into the slide (outer and inner barrels, gas system, etc....).
Although thinking about it now you could probably buy a used or broken pistol here and put your parts into it to make it work again. It may even be cheaper.
Best of luck to you.