OK here's the strange bit... It's a FW05R rubber as stated in the instruction that came with the car. Plastic upper deck and all. But the car came with foam tyres. I assume the former owner fitted on the foam tyres without doing anything else.
An email to a LHS told me that they could order the conversion kit for me.
With all the aftermarket brands, it's pretty confusing what's hot and what's not. So I will stick with the Kyosho kit. Hope the LHS doesn't pull a "sold out" stunt on me.