A recently developed, Landau-Zener-based quasiclassical trajectory surface-hopping method for medium-sized organic molecules is used to investigate hole transfer (HT) in the formally symmetry forbidden hole transfer process in bismethyleneadamantane cation radical 4a and its d(4)-labeled analogue 4b. The calculations involve sets of 200 trajectories, sampled from a canonical ensemble at 298.15 R, to directly calculate the mean first passage times, tau, for HT in both systems, together with Fourier transform analyses to identify the important modes which induce hole transfer. Very small tau values for hole transfer are predicted, despite the fact that the reaction is nominally symmetry forbidden. The main symmetry breaking mode is identified as the torsional vibration about the terminal methylene group on the one-electron, pi bond. An approximate secondary kinetic isotope effect is calculated, and is shown to be largely attributable to the change in frequency of the key torsional mode. The magnitude of the electronic coupling at the avoided crossing region for HT in both 4a and 4b is estimated to be 0.01 eV, placing the HT process within the nonadiabatic regime. It is found that qualitatively, the calculated tau values and the derived approximate secondary kinetic isotope effects are fairly insensitive to the method used to identify the avoided crossing region in the trajectory calculations. It is concluded that the trajectory surface-hopping method described herein should provide useful qualitative insights into the effect of nuclear dynamics on ET and HT processes occurring in a variety of structurally complex systems of chemical interest.