There are very few 54" tubs out there. For many adults that actually take a bath, even the standard 60" tub is too short. Every brand has their own name for white, and some have more than one. Also, differing materials and lighting can make even 'same' colored whites look different. Keep in mind that tubs are measured from studwall to studwall, not between finished walls. Might you actually have a 60" rough opening?