Looks about right to me. The pad's on bone rather than being too low on the cartilage.
Mexican grakles are awkward to fit. Three things to watch for
(i) the rings don't rub the projecting cheek bone
(ii) the lower strap buckles don't sit on the jawbone
(ii) you don't leave the lower strap too loose. It might seem kinder but not only do you lose the full action (which is weaker than a standard grakle because of the distance between the straps) but the pad will slide downwards and loosen the whole thing.
The noseband needs to fit so you can get a finger thickness under the pad IMO, not two fingers as usually stated, because it's then too loose to do it's job of stopping the horse crossing it's jaw. But others will probably disagree :)
Hiya we call them grackle nose band it looks ok to me in the older ones there was no rings it had leather loops.
Thanks for shareing your picture.
My frends horse john use to have one that was 15+ years ago now.