187 seems likelier. There's already a hierarchy among Roger, Gaban and Ray based on the preciousness of the metals in their names:
Gol D Roger
Silvers Rayleigh
Scopper Gaban
Anyways, heightscaling is mainly only valid if there are other patterns like this.
E.g Garp being 287 cm and Sengoku being 278 cm works as a confirmation of Garp being stronger, because they are both legendary Marines, fought Roger, are friends etc.