guver, you are right, I misunderstood the question.
I've not heard of switching the rx and tx crystals. I don't know if it will work or not, it very well may. I am sure that, as far as the FCC ios concerned, it is not legal.
You should be able to tell where the "new" channel would fall by looking at the frequency imprinted on the rx crystal and and compare that to the existing channel frequencies.