Skip I flew a Sportstar from Jandakot to Gladstone Qld a few years ago, slightly slower than your Z but with similar endurance.
We waited in Perth for 2 days of rain before getting out and making it to Kalgoorlie. 4.0 hours tacho time into a headwind. There we waited for another 3 days of rain. This weather of course was moving West to East so we could not count on any of the dirt strips through the middle being servicable.
The next leg was Kalgoorlie to Forrest, a long one, 4.7 hours punching a headwind and sitting under a cloud base of 2500 feet. It was the first and only time I have had to mark a point of no return on a flightplan. Due to the rain there were no alternatives for a diversion, it was either make it to Forrest or go back to Kalgoorlie. Easiest nav though, just pick up the railway line and land at the airport - there's only one, so you know it is the right one!
From Forrest we headed south east to Eucla ( no landing here ) to pick up the coast as I wanted to fly the Bight ( and it was spectacular ) around to Ceduna, 3.9 hours. Filled up & then overnighted in a nice cabin at the caravan park, they even picked us up & dropped off.
Next day was Ceduna to Port Augusta for a fill up, 2.5 hours. Then on to Broken Hill 2.9 hours. Lost a tyre there on landing so had to drag the plane outside the gable markers & tie it down there on the side of the strip as by then we were losing light.
Next morning got hold a new tube & got it fitted by a helpful LAME. Then departed for Bourke, 2.7 hours. Overnight & fuel there.
Last day was Bourke to Roma, 3.6 hours, for a fuel stop. Then Roma to Gladstone 2.9 hours.
All fuel was Avgas, all landings were on sealed runways at airports. Not a single leg gave me a tailwind, but that is a talent I have, I can find a headwind anywhere. I would have loved to have done the servo thing on the Nullabor, but as we were chasing rain I couldn't count on any of the dirt strips being usable. Maybe next time.
Hope this helps,
Mick