Thanks for the photo.
Looks like this part - https://www.sjsportscars.com/parts-a...SJ065C0002.htm
It is possible to measure the spring, but you may need to remove it from the damper/shock.
Fitted Length = measure the distance from perch to perch with the car's weight on the spring.
Free Length = measure the length of the spring with zero load on it. You may be able to slacken the adjustable perch to the point where the spring is loose.
Wire diameter = with a calipers you can measure the wire diameter
Inside diameter (ID) = again with calipers measure the OD of the collar of the spring perch (again looks like you can slacken the adjustable perch enough to gain access)
Looking at the photo I would be concerned that the body of the shock/damper is too long, thus reducing the amount of allowable travel under compression. By the looks of it these would hit rubber leaving very little travel under bump. Europa shocks typically have a very short body to allow for enough bump travel.