The front bumper with brackets weighs 40#'s. So going to a glass one is around a 20lbs savins. I have a set of AAR bumpers here if you need actual weight.
I wouldn't change hoods... Not worth it to end up with a crappy hood that bows really bad on the big end. If you want to put the car on a race diet, but not have a gutted looking car there are plenty of things you can do without cutting anything. If you still street drive the car, well then it becomes harder to do. Simple thing like removing the sound deadner from unde the carpet is worth 20lbs IIRC. Heater box, and wiper assembly weigh quite a bit also.
ALOT of "tricky" ways to lose weight if you are will to do a little cutting, and drilling...
BTW my GTX is 3430lbs with me in it. All steel except the hood, and still has stock seats front and rear, carpet, headliner and door panels.
Jeff