As of 3 weeks ago (when I left Darwin) you could pretty much get a job with 300TT without any hassle. SOME of the lucky applicants were able to remain in Darwin! IMHO, if you went to one of the larger operators in DN, you could be flying multis in as little as 6 months!
As mentioned earlier, you could easily get the required hours in 12 months (for Rex and Qlink) and 18 months would see you with enough for the likes of Virgin or Jetstar.
Your age shouldn't be an issue (I started flying when I was 38!) and the regionals are looking for older guys, as the older guys might prefer lifestyle over big$ and flying a Jet.
But you might want to consider your partner. Mrs DIVOSH and I had discussed a few years ago that I may have to spend up to 18 months interstate flying before I had the required hours to get into a regional.
I spent 7 months in Darwin, and one of the reasons I came back was that our relationship was beginning to show signs of stress. (Not helped by me only coming back from Iraq 2 months before going to Darwin). Flights to Melbourne are cheap from Darwin and I was home for a few days every month or so. Not all partners are as sweet and understanding as mine is (she's looking over my shoulder as I type this).
It IS hard on the partner that you leave behind, so think carefully before going.
At least you've got options these days.
Enjoy whatever choice you make,
DIVOSH!