Thanks for looking in, I looked at the Leopard but I am a cheapskate and Bulldog wheels were not only cheaper, I almost had enough sitting here to do the job. I could have waited till the HL Challenger came out, and used the lower hull as is to make the Challenger CARRV, but I had this KV1 hull here and thought...it's close enough.
The Chieftain tracks are actually really similar to the Bulldog jobbies, they have triangular links, with rectangular pads. If I am feeling really bored I can modify every track pad on the Bulldog tracks to the correct shape. 
If your friend can get me onto an ARV I would be over the moon, the huge problem with all pics of tanks is that no one ever gets a top down shot, so apart from blueprints we never get to see all the little details and how panels go together etc, which on a build like this is what I really need. There is one at Duxford, but that's a bit of a trek from our neck of the woods.
I have spent this evening removing all of the lugs from the inside of the hull, and blanking them off on the inside so that I can fill them...there are loads as I clipped out the exterior KV1 hull mouldings, there are pin holes all over the place. The driveshafts have a transmission cover that pops off, but underneath is a thick reinforced plastic ring that is moulded into the hull. I have sanded down one side but it took a long while.
And just in case anyone wondered about the suspension arm, I fixed it in the end by drilling a hole through the arm where the pin should have been, and pushing a short piece of brass rod in. It's all secured with araldite and the arm is at the correct height, so that's all good now.
RobG
It would be interesting to know what the diameter of the leopard wheels is. I am wondering whether they would foul each other when the suspension compresses, The front road wheels that I am using almost touch the KV idler.
...says he, hopefully...