Willie is really the 87 convertible expert around here. Basically, all 87 Camaro convertibles are marked as special edition, or had a map pocket with 20th anniversary edition printed on it.
The stripes are correct for a Z28. The flares near the tail lights probably cover the holes from the 3pc spoiler that was removed in the convertible conversion. Pretty sure the dash plaque instead of the map pocket means it was a ASC conversion and not a factory convertible... The runners look like stock equipment to me, but the rust proofing is a bummer.
Do a search for threads by Willie... Here's a pic from one such thread.