I was inspired by another user who did this on their classic so here is my Mint and custom 128GB iFlash Solo (running 128gb Micro SD) iPod Classic 5th Gen with this
Amazon.com: FLEANE FIP02 - Adaptador dual micro SD para iPod Classic iPod Video 5ª 5.5ª 6.5ª 7.5ª 7.5ª TF Tarjeta Adaptador de Repuesto MK8022GAA MK1634GAL MK1231GAL : Electrónica
Sustitución del Disco Duro del iPod 5ª Generación (video) por una Tarjeta de Memoria CF o SDHC/SDXC - Guía de reparación iFixit