Castlereagh and Carnarvon Hwys

I have very recently travelled most of these roads and I did the rest a couple of years ago. Assuming you're going via Dirranbandi and past Lightning Ridge (the route from Mungindi to Collarenebri has a section of variable dirt in the middle, and some roadworks in the northern bitumen section), then I can't recall any single lane bitumen sections. But I wasn't keeping score. My recollection is that the roads were generally ok. You could double check on Google Street View.

St George to Moree is two lanes all the way. You can check these roads yourself by using Google Maps Street View - example Castlereagh Hwy. Use your cursor to spin the street view around to look both ways.

Thanks. I just looked at the satellite image and it's high enough resolution to see the line markings. I'm a bit paranoid, because when on the Gold Coast Expressway, a number plate of all things, lying in our lane flipped up, jammed against the sump plug causing it to leak. Fortunately it fell out when I found an exit and could safely slow down.

Dubbo to Roma on the Newell, Castlereagh and Carnarvon Highways is dual lane (wide single lane in both directions). Provided the on coming traffic stays in their lane, you don't need to move oot of your lane.