I've been fighting a brake issue for 10 years that no one has been able to solve (slow response, but good force if you wait for it).  I decided to upgrade to modern equipment.  As much as I hate having non-factory items under the hood now, good brakes are cheap life insurance.

I don't have to preach to others about these cars, but the rear axle is a weird C-10 truck variant, different than what I'd expect, and different from what I assume came in the US Impalas.  Wilwood calls it the C-10 flange anyway.