No, thats illegal. Slapping RST tags inside a bonus shell doesn't make an RST. Just like slapping Rolls Royce tags in a Metro doesn't make it an RR.

People take the risk, and equally I'm sure theres plenty of 80's/90's Fords out there that people own who believe they are truely genuine Cossies/RSTs/whatever that are actually lesser models.

Really depends if you want to be on the right side of the law and also how much you really care about it saying RST on paper.