Those legs are solid brass and made to spec for Mapleshade and are also quite pricey. I'm afraid you'll have to peruse the threads here or go online to find something that would work. Hopefully someone here knows of some decent cones of differing heights that would work and can chime in.
I don't see how Nobsound springs would work since you'll need much higher ones up front than the back and the springs seem to need a level surface to work properly. Good luck.
All the best,
Nonise