If you are looking for established events to become part of the series then I strongly endorse the NSW vs Qld Challenge at the Tamworth Cup. The Tamworth Track is awesome and would be really well suited to F1. Plus they have the best facility of any EP10 ONR track in the State (covered pit area, lights, toilets, showers, camping on-site, best canteen of any non-commercial venture, etc.). I know they're currently organising this year's event. If you need a contact PM me and I'll provide you with one.
The Newcastle GP is another established event that gets good numbers, and has a top-class facility. I'm not sure if it was part of the F1 Series last year but I'm sure Glenn Sidney would be glad to hear from you if you wanted to include it. Again PM me if you need a contact.