Thanks Chris, I looked at a range of options including twin plate. The Isuzu clutch 6x6 was rated at 600 ish, so that cut it out. The Viper ended up being too much hassle and to be honest it was in the basket of a custom set up in my mind. The flywheel, and existing clutch had to be sent to Brisbane and then a replacement set up to suit.It needed either a new flywheel or machining and re-drilling - they could not be certain. I could not expect a workshop to have the barge sitting around for a week whilst this was going on.It was just too much stuffing around. I think their product is the goods, but just didn't work for me.
I have decided to go with the Exedy Safari HD ex BD as they and Exedy are standing behind it with a 2 yr warranty so regardless of how hopeless BD are, Exedy have the runs.(rated somewhere in the order of 900 continuous and 1200 peak, so will see how that runs - took a lot of hassling to get these values) i contacted UFI re their HD cluch - @AB is running one. Could not get the info or feeling of certainty out of the guy I spoke with - all he wanted to do was clap on about how crap the chev was - good bye fool.

By comparison, the Clutch Industries unit in mine was running in a guys vehicle in WA, the guy who has a similar set up to mine, and he put 100,000klm on his, but the flywheel has toast by the time he swapped to an auto - and he towed a 3T van from Bunbury to Cape York return with that under rated clutch. Either, he is a total animal, the clutch is very de-rated, or he wasn't getting the torque he thought.

Right now I simply want the beast sorted with the belt issue and its then more or less capable of getting back on the road. Aircon needs a couple of hoses and gas, then slow burner wire tidy up. I am looking hard at the Interchiller setup to get the inlet temps down and resultant EGT's (Torqueline Garage can do a completed W2A and A/C chiller system, will see how everything sits for now). I have to still hook up the water injection system as well - plenty to do. Hydro Boost is perhaps the next ticket after the clutch I think.