Hello, all im wanting to know is what size "jighead" i need for my new burkley gulp, and also powerbait.?

Alright all im wanting to know is the size i need, i have never tried this before and i want to give it a shot i have seen on a fair few fishing shows that this works on sandy bottoms for Flatthead and even mullet as such, i live down neer a town called Mount Gambier n fish around near Port mcdonald.and im only in roughly no deeper than 12 ft of water were i want to be using these baits. these baits are small the powerbait is 46 mm long and the burkley gulp is 6cm in length. Thanks anyone i really just need to know the size n weight of these jigheads any info will do a heap! thanks Ryan.