I just did this exact swap. (I will be doing a write up soon) You would be suprised at all that is neede to change. Just wow.
Doing the swap I found out at how many things on the 84 are different. and had to be changed
(This is no where near a complete list) (to do the swap)
oil pressure switch
Backup light switch location and switch itself
Air box, (have to cut the frame to fit a later year)
So it WILL fit and work, as proof there is one driving around Vegas now, but it is not plug and play.
(A write up will be coming)
"DRIVE IT LIKE A FIERO"
engine to be determined '87 Duke (Sold)
'87 Quad 4 H.O.
'87Blue GT 3.4L Swap Completed!!!!!!!! Boosted!!!!!!!
^^^^ Now in the Construction Zone^^^^
Las Vegas Fiero Club Parts/Sales/Service/Club
Fiero Road Club Of Northern Nevada