I ended up having my CSi tank repaired in London, as adapting a CS tank turned out to be far more complicated than I had hoped. I can't remember exactly what the issues were, but I think from memory that I couldn't work out how I could replicate the arrangement of the 12 or so holes with threads where the sender screws into the tank. It's worth mentioning that the tanks generally corrode from outside, in the seam, due to water sitting in the boot / trunk. My repair worked out very well and only cost me about £50 I seem to remember.