In this work, we exploit the spatial dimension of spectrally-spatially flexible optical networks (SS-FONs) to perform path selection. The existing path selection schemes in SS-FONs predominantly use k-shortest paths (KSP) method. However, in this work, we demonstrate that in SS-FONs, consideration of core selection along with link selection between source and destination nodes can significantly increase the spectrum utilization efficiency. We propose a k-core arrangement based paths (KCAP) scheme that performs path calculation and prioritization on the basis of core arrangement in different multicore fiber (MCF) structures, threshold crosstalk (XT) values, distance adaptive modulation (DAM), and the number of MCF links. The proposed KCAP achieves better spectrum utilization than the existing XT-aware and predefined core-prioritization schemes.