Having embarked on my RSR back date project, I have decided to stick with steel quarters and front fenders with fiberglass flares. I went back and forth with the whole FG thing like Jack's but I'm actually going to be getting things done more cheaply by sticking to steel fenders. Part of the reason is, I have managed to get some REALLY good deals on various parts (particularly the front fenders) front the board here and ebay. The best thing about sticking with steel front fenders is the ease of fit. Bolt them on (basically).
The rest of the car: hood, most likely doors, duck, and bumps will all be fron GT Racing. I have IROC parts on my Carrera and am very happy with fit/finish. Plus, they are a local company for me so I save shipping (major) and Hank is just a really great guy...
Have fun, here is the state mine is in currently, hopefully the motor/trans are coming out next week and I'll be rolling into phase two of MANY