Weight Difference with Fiberglass on a '67

How much of a difference would exchanging the steel body for a fiberglass one make in terms of weight? I'm looking to do this to s '67 Chevelle. The factory weight on one of these is supposedly 3,415lbs. Some I've inquired about this on other forums, but I've gotten too many answers, ranging from "If you make it fiberglass, the whole thing will weigh 1000lbs total", which is a bunch of bull, to "It won't make a bit of difference". Any estimations?

it should make a signifcant differnce dont qoute me on this but prob take off about 400 lbs for the whole front end which should make you about 1-2 secs in the 1/4 again dont qoute me on the wight numbers and 1/4 mile numbers as i am only bout 80% sure

80% makes a pretty good probability for me

You wont loose anywhere near 400 lbs off the front clip by going to fiberglass. The whole stock front end doesnt even weigh 400 lbs.

I went to a fiberglass front clip on my car ( 64 Malibu ). The whole clip in " drag race weight " f/g construction weighs maybe 40-50 lbs. The stock front clip I would guess weighs in at 200-225 lbs at most.

I replaced the front clip to my custom 66 chevelle with fiberglass. Looked nice but if I had it to do again I would stick with steel. I would say you would save about 100-125 lbs, depending on wether or not you go with inner wheel wells on it.
The fiberglass is not ready to paint and is not perfect, it will need bodywork prior to painting. Steel is pretty much ready to go. For every 100 Lbs saved you gain 10hp. If you are going for a full body fiberglass for racing purposes expect to save only a few hundred Lbs if that. I have lifted the body of a 66 in the air with a few buddies and it wasnt to bad. I have also lifted a Corvette body in the air and it almost seemed more heavy. There is still steel in a fiberglass body and a lot of reinforcements in crucial areas. Up to you, but hope this helps you.