The pre 88 brakes are single rotor systems. the 88 brakes are a double rotor, center vented disc design. The caliper is wider where the disc goes through it.
The orientation shouldn't matter. the goal is keep the bleed valve facing up.
I don't know much more about the 88 brakes other than the 88 are a one year only and hard to get and I was under the impression that the bolt pattern/spacing of the caliper is different enough to not allow it. also, the 88 front rotors are hat with separate bearing design.
other than that, someone else should know more about why 88 brakes won't go on pre 88 fiero's
I would say upgrade to the le barron brakes or the grand am for better stopping power and availability of parts.
[This message has been edited by IFLYR22 (edited 05-19-2008).]