Unfortunately the likelihood is that these will go to Chiltern, in terms of commonality of rolling stock. Although that could release a couple of Turbos, so it's not impossible that
GWR▸ will benefit in due course. Although I don't believe the line will actually be operated by electric stock until the end of 2017 at the earliest, so if you were looking for a stop gap measure prior to
GW▸ electrification coming on stream then you may be disappointed. Unfortunately....