Gah, take 2, lost a long post!!
400m2 is the standard block size. In Lake Macquarie battle axe blocks must be 600m2. There are maps on both council web sites with all that info. Large blocks can be found as close in as merewether & Hamilton but they come at price. A. Purple if egs, Merewether 1200m2 block, house will probably knocked down 1.2M, Hamilton double block 1.3M, house has been flipped & sold for about 980K, they're building on the block, so they'll do well but the investment s high. Some other things to consider: there's lots of land for sale on the outskirts so make sure your numbers add up; the landscape makes blocks which on naps appear subdividable not a viable option; lots of houses have been built to both boundaries so not possible to subdivide without demolishing & only some suburbs would make that worthwhile.
Suburbs .....Kahibah & south, New Lambton & west, but lots won't work for either a landscape or cost perspective.
Good luck!!