For what it is worth, the frequency ranges for the GP300 (and P110) radios are as follows:
VHF
136-155MHz
146-174MHz
UHF
403-433MHz
438-470MHz
465-496Mhz
490-520Mhz
Using shift during frequency entering in RSS will allow for almost any entry, but radio specific VCO will only give you some leeway outside its own range, but not too much to operate well into the adjacent lower or higher ranges, specially for UHF models.
