As the chassis design is about 3 years old and was never used in the UK as we all went to the link car version, it won't be easy to find in the UK.
As said above, there are two easy options, either from the UK importer or from The Border, as the Netherlands tend to still run various pan cars on 2S. You could also order one from
Fibre-Lyte, they list the standard chassis and they can customise the shape for you. Or just strap the lipo onto the standard chassis, there is no need for the whole pack to be entirely on the chassis.