solid castings, unless this is a full time autocross vehicle. i've never had a problem with solid castings and until god reaches down and grabs me by the ear, twists my arm and sends me to autozone, i won't buy anything else for normal driving.
i may get the slotted rotors for the '87, but i don't think there is enough opening in the wheels ('92 z28) to be able to showcase them effectively.