You don't have to wait for replacement brackets for your 1/3 Pitts from GP. Get to your favorite hardware store and get some National Hardware shelf bracket clips. Cut off the tang from one leg of the "U" and the flange from the other, spread it open to the needed angle, and there you have it! The holes are already in the bracket and at the proper location. These clips are 10% thicker and 50% wider and they're "soft" steel so will not fracture like the GP brackets.

Regards,
DrGO