ok, so you are saying to buy a crew cab Fuso or NQR, leave the wheelbase as it sits and just make the two wheel drive crew cab into a four wheel drive by adding a solid axle and a transfer case?
If so, I think that is the best way to go for ease of construction, budget, etc. If I was going to do a full on custom build, I would get a cab and build everything else from the ground up. I have estimated about 25-30k in parts, no labour. So, if you had the cash and got a decent deal on the fab, you could have a fully custom truck (Crew cab, 4WD, 400 hp Cummins, lockers, basic flat bed, etc) for about the cost of a new FG or NQR.
I started a parts list in the previous post, lemme know what else you need. I can get with Matt on labour and his idea of materials cost and send you a bid if you are serious about us takling this. We will both be at the OvEx in a few weeks if you would like to meet there and chat. Adding a solid axle and transfer case into a 2wd truck is relatively straightforward (no cab swap and no frame stretch). I would guess a few grand in labour and then whatever you wanted to do for a front axle (2k - 7k) and transfer case ($500 - 4k).
Jon