you could pick two of the three, L98 t-tops, or WS6. but you couldn't get all three. L98 + t-top firebirds are very rare because most people who got a L98 formula were performance minded and wouldn't give up the handling package
L98 + t-top Z28's are much more common because the top suspension was a seperate check box on the order form that was often left blank. WS6 was part of both formula and trans am packages from 87-90 that could either be flat out deleted or would get deleted by selecting certain option and option out groups.