I think I went about the whole process arse about face. Paul did me an engine based on the original gear ratios and also on the basis of me getting hold of my own carbs. After the engine was done, I went for the longer box, which has been great in terms of improving cruising comfort and economy (cruising comfort was the main reason for doing it) but has left big gaps between the ratios. The carbs are also a problem. They are a pair of DCNFs that I picked up cheap. After fitting them, I got the van on a rolling road and asked the guy to set them up. He did the power run, but didn't actually change anything - he said they were OK, but what I had asked him to do was to set them up, not do a quick check. The carbs need sorting and I think that will improve the low speed running, but they are a pig to start when it's really cold and I don't now want to start throwing money at parts and set up labour on something that might now work out in the long term. Having run the van for about 5,000 miles on Paul's engine and with the new box, I certainly have a more focussed view of what I need!