IMHO, go with a Mach1 rear 250, or something like an HR Super Race 260-300.
*I* don't like any of the Eibach springs. I think they are all to low and too soft to be good for anything. Your rear springs are typical Eibach springs, a huge drop, but without the required increase in spring rate.
Note, the drops are approximate
Coil Spring Tech
You also have to be careful when comparing progress rate springs. Some may not get to their higher rating until mostly compressed. And, with stuff like Eibach, I doubt they even get to the rates they say until nearly in full bind. It costs less
to make the higher spring rates happen at more compression (less windings & spring/material). Eibach is all about cost and selling to people that don't know about the specialty companies for their vehicles.
If you want to lower your car for looks
, that's your choice.
I mentioned the above because it's also relevant to handling. IMHO, MM rear adjustable LCAs are a requirement to help tune the rear suspension height/rates.
BTW: As nice as coil overs are, *I* think they have no place at all on a mostly street
Stang (like mine). MY Stang is my daily driver in warm weather and it has to deal with the MEGA POS New England roads. My Stang is ~25 years old. And, I plan on keeping it many more years!
Part of that means not having the towers ripped the ***** out of by running coil-overs over POS streets.
So, it all depends on the exact desire/purpose of the mods and the use of the car. It varies for each
Hey, you wanted opinions. That's my two cents.