Are those pistons truly non-cylindrical or are my eyes playing tricks on me?
That's part of what makes them so appealing. I've never heard of non-cylindrical caliper pistons before. This is all-new to me.
Having no idea where those calipers came from, I similarly have no idea where a person would get rebuild kits for them. I'm good at doing no-parts rebuilds on calipers, though. And he says the pistons move freely as-is. But aluminum calipers are known for corrosion in the seal grooves.
The pistons appear to be phenolic. Phenolic pistons are WONDERFUL...when they work. They're an insulator, which keeps the heat from braking from transferring to the brake fluid. But the phenolic pistons were a seizure waiting to happen when Chrysler started using them. The big aftermarket "fix" for seized phenolic pistons was to force them out using a 2000-psi grease gun for pressure, and then rebuild the caliper with a normal steel piston.
Also I wouldnt advise using these brakes on a 400. look at how the rotors have scored the top of the caliper from contacting it. thats because the pads are pulling the caliper down on heavy braking causing the top of the rotor to contact the inside of the caliper. had the same issue trying to use a modified caliper mount when i did my SAS.
I didn't see that at first. It is something of a concern. Makes me wonder if the rotors are stock diameter, or somewhat larger. At least one rotor is slotted, but they may be a mis-matched set--the other rotor seems to be more rusty, as if one was original and one was replaced.
If the price was right, I'd be willing to try 'em and see what happens.