Hey, a fellow Australian sound editor. First up Rabbit Ears Audio have a bunch of tank libraries. You can buy them separately or in a bundle here: http://rabbitearsaudio.com/rea005-military-vehicles/
Are you in Victoria per chance? I was actually out at a track that has WW2 era Centurion tank. Though the Rabbit Ears library doesn't any recording of the Centurion tank, they do have other WW2 era tanks - including ones that sound pretty similar to the Centurion. However, I unfortunately got to the track too late to record the Centurion. Their website is http://melbourne4x4.com.au/?page_id=38 if you'd like to swing by and record it yourself. Or if you're not in Victoria, maybe we could come to some kind of arrangement?
For planes, the Sound Librarian has a couple of period/WW2 planes in their collection: http://www.prosoundeffects.com/the-aviation-collection.html
And here's the Boom Library historical firearms library mentioned before: http://www.boomlibrary.com/boomlibrary/products/historical-firearms
And the Blastwave warfare packs that were also mentioned : http://www.blastwavefx.com/Warfare/c59/index.html
Some of these packs are pretty expensive though - but they do appear to be pretty comprehensive. Lastly, for reference material, Youtube is a good starting point for finding videos of period vehicles/weapons. After hearing what they sound like there, you may even find you can design convincing effects using your existing sound library. Good luck!