These are a hard-to-get part now, I didnt think BCP would have them as the original mould owners didnt...Im pretty sure someone who works with fibreglass could modify a wrap around one?
Dave, I've got a new rear bumper, came with bits from my 1984 280i convertIble. Definitely ribbed/wrap round with single cut away for the exhaust. PM me and I'll post a pic' if required. J C.