I talked with guy who may be making a new dropped spindle for the Impala yesterday. To answer the question about bigger breaks working the answer is, No. Unfortunately there is no way to fit any bigger of rotor than stock. As far as fitment goes he is working on the design right now to keep the wheel in the exact location unlike the Bell Tech Spindles that push the wheel out about a 1/2" Also he is working to make sure that there will not be any problems with clearance on 17" wheels like the stocks which I think he said Bell Tech had. The price should still be $229 but I forgot to ask if that included the rear springs.
Speaking of springs he will have some available very soon for the SS. I believe they are 1" drop all around or 2" all around and they are "progressive springs" He told me that after looking at the prices of current springs offered for these cars he should be able to offer his significantly cheaper!
One last thing, he asked me to ask if anyone out there had a set of Impala stock spindles he could borrow for a short time so that he doesn't have to take them off his car. He would pay shipping to and from and also gladly give the lender a "great" deal on either a set of springs or spindles(if they are made).
If anyone would like to loan their spindles let me know.