Nick:

I had the first fastbuild IV-P fuselege and installed the aileron crossover per the manual.  I had no problem with the radio stack but the whole panel was planned (by me) to use the available space so maybe the problem you refer to might be trying to fit one of the many available  "custom" panels???  Anyway, I did fit a King 89B GPS  right above my 6-pack steam gages and also got  the roll servo for the STEC 55 behind the panel on the right side.

Hope this helps.  Best Regards, Bill Hogarty