The phrase "hadst the right to" implies a sense of entitlement or authority over something. There are several synonyms that can be used to convey similar meanings, including:
1. Had the privilege of
2. Possessed the power to
3. Enjoyed the advantage of
4. Held the authority to
5. Was entitled to
6. Had the ability to
7. Were authorized to
8. Had the permission to
9. Could rightfully claim
10. Owned the prerogative to
By using these synonyms, you can add variety and emphasis to your writing while still conveying the same meaning.