So every spring you buy is sitting too low? Sounds like you need heavier springs.
There are many options for springs out there for these cars. Here's Eaton's website, and as you can see there are multiple offerings in part numbers for these cars, depending on desired ride height, heavy vs std duty, engine sizes, coupe/convertible, etc:
Rather than going thru a 3rd party to buy springs, I'd recommend chatting with their tech support directly so they can assist you in your decision.
The fact that you have non-standard/oversize tires will complicate things greatly, and my require quarter panel/wheelhouse modification to fit if you really want to run whatever wheels/tires you have.
If you provide specifics of exactly what you have, maybe someone here with a similar setup can help. But I believe you will need to provide tire size, wheel size, exact spring part numbers you have attempted, etc.
