Well after a long hard look, I realised that i wasn't going to get exactly what I wanted (well for the budget anyway).
So a compromise had to be reached, I traveled to the Czech Republic and found the nearest thing to what I was looking for, did a deal and now I am the proud owner of a Tatra 815-2 6x6 V8!
The truck started life as a hook loader, as I type the hook loading equipment is being removed, the cab is only a day cab but that also is being removed and replaced with a sleeper cab.
The chassis is being extended by 1m to facilitate the body length I want and the twin back wheels and the front wheels are being replaced with super singles.
The cab will be refurbished inside and out and the chassis will be freshly painted. That ought to give me a good base to start with.
All this work is being carried out in the Czech Republic where Tatra parts and expertise are in abundance.
I am due to collect the truck and drive it home sometime during the next few months. I should have pictures of the truck before then.
Here is the latest after removal of the hook loading equipment.