We determine semi-classically the eigenvalues of a He-benzene model where the benzene is held fixed in space (and non-rotating). The results are analyzed with an efficient approach toward extracting the eigenvalues from a short-time (set) of correlation functions: cross-correlation filter-diagonalization. The use of this analysis tool allows quite accurate determination of the eigenvalues, when compared to exact eigenvalues. One of the reasons that the eigenvalues are so accurate is that the cross-correlation filter-diagonalization approach allows the use of very short times, for which semiclassical is very accurate.