I am not a Buick expert, but I would have to say you could probably get away with just about any kit if you build a caliper adapter. Currently I am running 4th gen Camaro brakes on my 3rd gen Camaro with just a couple of changes. First is the fact I have the hub and rotor as one from the factory, turn that down to just a hub and I am now able to run the 4th gen rotor. Next was a bracket that connects to my spindle to hold the caliper on, cardboard works wonders. Lastly it was making sure my spindle was not in the way. I had to do some trimming to that to make the bracket and caliper to fit properly.
Or you could call a company like Wilwood/Brembo and ask them about the possibility of getting help.
My guess is you are going to have to retro fit almost everything for that car. Due to its "Grandmother" facade not many companies would take the time to produce parts for it. Some of the woes of trying to be different.
Good news is once you find the size of different items, spring diameter and height, shock/strut height, etc. you will be able to pick out what you want. There might be some slight modifications for mounting locations and such, but they will eventually fit.
You may also want to look into what parts will swap over from newer generations of Park Avs.
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