E30 Zone

I want to use my 90/04 build 325is MTech as a daily driver, it's been summer driven only for the five years I have owned it and I want to have fun all year round! I want to revert back to the factory suspension.
It was imported to Canada from Japan just before I got it and it had been lowered, previous owner had left the old springs in a box in the boot. Box was marked COBRA 001446 - BMW E30 6 Cylinder full option. I checked their website and for this product it states that it would be 40 front and 40 rear, does this mean it's lowered by 40mm? Other than this I have no idea what's been changed.
The original (I guess) front springs are @310mm long and the rears appear brand new, they are @190mm long.
My question is: Would the lowering have included new or different shocks? Are these spring lengths standard?
Any advice would be appreciated, I want to know before I start taking the suspension apart what I'm getting into.

I have attached a pic so you can see how much it's been lowered roughly.
Thanks for your help.

Strange, on closer inspection it looks as though the original springs have been left on the back, they are still fairly clean and black in colour - the 190mm long rears are greyish/white, appear brand new and match the colour of the front springs. Maybe the previous owner decided the fronts only should be changed.

I want to get away from the very solid, harsh ride and very low ground clearance so I need any advice as requested - would it have been a spring change or shocks as well possibly?

BTW, the car has only done 64,600km, @ 39k miles so it's all looking as new original paint and no rust or oxidisation underneath so I can see what's original and what's not.

Any ideas? Am I correct in my estimation the fronts only have been changed and it would be springs only?

I hope so - my next question will be how big a job is it ro re' & re' the old front springs?