Danyel is best to answer your questions. This photo is from one of his threads:

Notice the offset from the top bolts to the bottom bolts. Most universal kits are straight up and down with the mounting plate where with the Fiero, the lower hinge plate has to be offset inwards. I have seen one person use a kit for a Honda Civic. He had to cut and weld a new mounting plate as well as use 2 thick pieces of steel plate to space the lower hinge mounting point. If you have access to a welder it may be fairly straightforward.
Also if you notice in his picture, Archies kit was a 2 piece kit. There was no steel "C" plate that spanned the entire length of the frame. The top Lambo hinge bolts only to the top factory hinge location, and only a bracket for the dual shocks mounts on the bottom hinge location. This is similar to what Archie did:

[This message has been edited by IMSA GT (edited 04-15-2015).]