I don't know what's factory for that car but the picture (your link) shows 4x progressive springs.
The front springs on a mirage need too have the last link spaced off a little bit because how the spring fits on the end, but a progressive wrap has the "easy/squishy" end more tightly wrapped together, so there's more coil per vertical inch, so there's less space between the wraps.
My concern would be the spring would sit incorrectly and not rest how and where it's designed to, solely because of the tighter wrap, and cause damage to the strut, and eventual catostrophic failure.
It also could just simply be the wrong diameter.
It could also fit and work great.. ya know?