This study constitutes an effort to assess the relevant issues which should be addressed in order to adapt models currently available in the literature to predict final particle distribution resulting from radial centrifugal casting (CC) of particle-reinforced metal-matrix functionally graded composites (FGM) to the conditions prevailing in longitudinal CC. As such, a comprehensive review of a set of those models is performed, in order to ascertain the methodologies, the physical assumptions made, and the inherent limitations in applicability, so as to clearly identify the main deviations from the physical conditions prevailing during longitudinal CC. That review is then complemented by evidence of phenomena observed in longitudinally centrifuged FGM composites which are not in accordance with the physical assumptions admitted by the examined models, thus illustrating some of the issues which must be catered for in any successful effort to establish an adequate model for longitudinal CC.