I thought that this model fuse put this to rest a long time ago. You can clearly see the differences and where the GM F body will not clear the body. This is more than cosmetic and it's a matter of where and how the firewall and engine sits in the frame. As said before, this would be like trying to putting the skin of a lion on the body of an elephant and it's the places where it won't cover that end up making the car look bad. If you are looking at saving $5,000 by going this route and it's the major reason for doing so, some friendly advice is to rethink building a Lamborghini replica because $5,000 doesn't get you very far in this hobby (personal experience has proven this about $30,000 ago). I continue to read about "stretched Fiero's" becoming a safety concern and I can only suspect these comments are made from a lack of knowing what's involved to do this correctly. I cannot recall a singe story of someone having a frame break apart on them and we need to remember that most automobile frames are simple pressed stampings welded together to create a box. Most all of the stretch jobs that I've seen are actually on the side of "overbuilt" when compared with what GM used then or even uses today.
Thanks,
Chris