haha, thats cool as! I did this years ago with the seat from a Civic MB1 SR, was comfy as hell! Mind you, that MB1 seat would probably be worth something now, was in mint condition too. Can't remember if I ever took photos of it or where it ended up!
Interesting about the metal fatigue though, one to watch out for. Seat may also have been in a crashed civic? Hard to tell really but best to check ours to be on the safe said. Ta for the heads up mate and totally rocking that chair! (hehehe, see what I did just there!)