You are still stuck with OPCD on the Secondary under 450.3(B)...
Primary only protection is disallowed by 240(F) which means that you must use line 2 from the table: PRIMARY & SECONDARY PROTECTION.
I have in my day installed a ton of dry-type delta-wye transformers. Without exception the AHJ looked for the secondary OCPD --- RIGHT OFF THE BAT EVERY TIME.
It remained on their hot list of common electrician errors.
I can't speak for your AHJ, but out here they are on this like white on rice. You'll get red-tagged every time.
