Well, I'm absolutely stoked! I've just had a 30 minute contact with Peter, VK3EPW, who's in Melbourne.
Both of us running home brew transmitters. (He's running a home brew receiver too, but I'm not quite at that point).
Peter gave me pretty good reports, I'm around S8 to him, sometimes fading to S7 when I'm hard to read and sometimes peaking at S9 where I'm easy to hear. There's a fair bit of static from storms around tonight for both of us but we had a fine contact and my simple transmitter apparently sounds very good. "Sounded like a bought radio".
One question that came up for both of us, and I'll have to research the answer is: can a direct conversion receiver receive a double sideband transmission?
Feeling very positive about home brew radio tonight, but now it's time to go sleepy ni nis and dream of the next project.