The receiver antenna is the least of our problems with trying this!!!
Probably the easiest thing to do is get some crystals in the same range as the controller (i.e. the 27 is 27.145, and you could get something within the same range, like a 26.9).
I think there was someone on the board who did this (Nightwing?), but I don't know the source for the crystals, or the possible ranges to swap for.