I have a CR Sebring and since it is a cousin to the CR Cobra, I will attempt to figure out what you have.
The lower control arms and struts are stock MII. The upper control arms are aftermarket, the original MII parts are stamped steel. The cross member looks just like the one that was under my Sebring before I modified it for standard coilovers.
The lower part of the coilover appears to from a kit like this one:
https://www.speedwaymotors.com/QA1-M...b-,263210.html
There are a few companies selling versions of this type of MII coilover conversion. Typically, they use a barrel shaped (tapered) spring that fits a 2" coilover at the bottom and is large enough to fit the stock MII spring pocket at the top. I have a much older version of that type of conversion above on my 46 Ford street rod with stock MII suspension.
Yours has been possibly modified to accept a standard coilover spring that is straight. Hopefully, a proper spring pocket was added to the top to keep the spring centered over the shock. If done right, the upper shock bushings do nothing but hold the shock rod. They should not support any weight of the car since they are not designed for that. The spring loads should be supported by the cross member.
I can't remember what the spring rate on my car is. I can check when I get home. I haven't gotten my car back on the road yet, but the rate appears to be about right.
Hope some of this helps.