Im a little confused....suspension gurus step inside!

[A-Guy]

Well I have a 1972 Chevelle that I want to lower about 3" and Im a little confused about how to make it happen. Would just drop springs do it and how do drop spindles factor into the setup. What are the purpose of drop spindles and are they needed? I would also be upgrading the arms and bars as well. Basically I want her to be ready for anything, autocross, track etc. I have not purchased them yet, but i will be running 19x8.5/9 up front and 20x10/11 out back. Any help/knowledge would be greatly appreciated, thanks in advance!!

Chris