First, welcome to the site!
Second, we have an entire Z28 section just for this.
(thread moved)
Third, you can pretty much bet it's going to be the LSA in the new Z28. As for weight, I don't know about that. You are talking track car here. Suspension upgrades galore. Shaving off weight? Have no idea how they will get that done. Of course, all of this is speculation...
Please feel free to read up on the many threads covering the topic and join on in!