Which way to go Syd to Gibb River road

would take me 6 weeks just to get from Sydney to Kimberly at my take it easy approach.

If you really pushed for time and looks like you are look at hiring 4wd and flying to & from sydney alternative have it flatbed up with plenty of time in advance fly up then drive back home

Just a word (wink wink nudge nudge...)

Its the Kimberley.

Some are a bit touchy about that

bill

i think you will have to travel both ways. Meaning a loop. It just depends which end of the Gibb you want to start at.
6 weeks is pushing it to be relaxing though. Still, it would be fun.
I'm heading there in early May starting from Adelaide/Alice/Broome/Darwin/Kakadu/Adelaide....... see you there!!!!!!!!!
I'm taking a few months though.

We did our home in Victoria to Halls Creek via Alice and the Tanimi in 4 days without pushing it so I'd say a week, week and a half from Sydney

Another suggestion would be to head to Bourke from Sydney, up to Cunnamulla, Eulo, Windorah, Bedourie to Boulia. Cross the Plenty Hwy and pop down to Alice Springs to top up some stuff. Cross the Tanami Halls Creek and on to Derby.
You can return from Kununurra by any of the routes suggested previously.

Six weeks is enough time to see plenty without rushing too much. Get a piece of paper, or whatever suits you, and work out a timeline. You can use this as a guide to keep on track. It can be handy to work out where you'll be topping up fuel, food, grog and water.

You said you don't intend to do any sightseeing but it's going to happen anyway. The drive across Australia is spectacular and I am constantly amazed by the scenery as we travel along.

We are usually limited to school holidays when we travel and to 4 weeks a year so I understand covering miles in short time to get places. We drove our Dmax fully loaded, but not towing from Darwin to Mildura/Wangarrata/Lakes Entrance last year and back home through Melbourne, Adelaide, Darwin (in 4 weeks).
Have previously driven the Kimberley etc from Darwin in similar periods and a 1 month road trip to Townsville and onto Brisbane seeing what we could and coming back inland through Roma etc. I've also driven to Perth from Darwin.
I would stick to the highways if you have already seen a bit. You could travel to Mildura, come out north of Adelaide and head up the Stuart Highway. I found travelling in Victoria painfully slow at covering any distances.
I personally would head inland NSW upto Roma, Longreach etc and go that way. Once in Qld there is little traffic out west, and reasonable roads so you can make good time. The secret is to getting away early (but not in the dark), and keep breaks short for fuel/coffee and a reasonable lunch break. Having a 2nd driver helps.
Once on the NT roads you can make good time travelling at 130kph if you don't mind paying the extra fuel and happy to travel at that speed. From Katherine its a 5-6 hours drive to Kununurra,
Once in the Kimberley, upto you which way you want to cross the GRR, whether you start in Kununurra or Broome, but you can get to Broome from Knx in a full day of driving, although it is a bit of a haul.
Our view is we would like to see more, but with the time we have we have to put the kays and time in to maximise our time at our final destination, otherwise wouldn't get to see any of it in our circumstances.

Put your car on the train 2 weeks prior, then fly to Darwin to pick it up.

Ive done the Gibb 13 times now from Sydney. I used to go via Cunnamulla Mt isa, but the kangaroos just over the border in Qld are or were in plague proportions so i stopped going that way. I used to do that section at night. Now i go via Broken Hill, Pt Augusta, Katherine then Kununurra. But i try to get to Broken Hill during day light hours once agin because of roos and goats. Leave sydney by midnight gets you to dubbo/nyngan by sunrise. then easy drive to Broken hill. Can usually get to Kununurra in 4-5 days, long days, lots of night driving. i have a Facebook group "Gibb river road and kimberley region"

Enjoy your trip.