Finding droop for corrective mounts – Scope matter?

I have scopes that are known to be perfect optically centered (via mirror) and some that I can’t center as reliably.

Would it matter if I used a known optically centered scope to determine the amount of droop adjustment required? … or do I need to use the same scope that I plan on mounting after the mounts are machined?

Mounts and distance between mounts to be the same.