I put an actual strut in my audi allroad with struts from an a6. i was looking to get stiffer and higher ride height, where or what model spring should i look for?

the car has 350k on it and the air compressor locked up and I did not want to put any more money into the air suspension so I converted it to traditional coil springs on a strut. I got 4 used strut assemblies from an a6 and it worked just fine, but the weight of the a6 is a tad lower than the allroad so it squats a little.