It's pretty obvious that they will choose Busselton Airport as a primary W.A. destination. It is rated CASA 4C and can handle fully loaded aircraft including A320 / 737 and A330. At one stage Jetstar was running flights between Busselton and Melbourne. Busselton is a holiday destination with access to the major wine-growing region of W.A. It's presently running a touch under 40K flights per year for FIFO bit that can be easily expanded.
There is also a plan to run Kalgoorlie Boulder flights but that won't be attractive to Bonza.
The next question is where from? Avalon VIC is quite likely, and SA and NSW airports will likely be involved.