DVLA accepted the corrected GVW listed for my 90 - I included a photo of the VIN plate showing the vehicle weights. Many others had done the same. Had it not been changed I could not have it tested at a car MoT station (forget the classes - Class 4?).
However, they would not correct the name of my TVR from "Tamin"- perhaps I should have sent a photo of the logo on the bootlid?