The zx coil spring is too large a diameter so you will need to cut the zx spring perch off and swap the 510 perch and spring on.
Strictly, you do not have to used coil overs to have an adjustable height.The zx struts are 1 1/2" shorter than the stock 510 struts and yes the spindle is at the same angle. The zx spring is way, way too large a diameter to fit up inside the 510 strut tower so it has to go. What you can do is carefully trim off the lower spring mount from the old 510 strut and trim off one coil from the spring. Removing a coil will increase the spring rate... a good thing on a lowered car to reduce suspension travel and firm up the ride. Not totally necessary but stock springs are always a compromise and on the soft side. Do the same to the zx strut and grind the remaining weld down smooth on the strut tube. Now slip the 510 lower spring mount and shorter spring on the zx strut tube and assemble with the old 510 top hat. To prevent the spring perch from sliding down the tube use a split collar that can be moved up or down to set the height.
Trim just above the weld on the lower spring perch with angle grinder and 6" metal cutting blade.
Tap the perch loos and off...
Remove and grind down the weld till smooth so the split collar can slide smoothly and grip the strut tube.
Loosely assembled strut with spring, spring perch and split collar underneath. The split collar will withstand 6,000 lbs each! That's almost three 510s on each split collar... they won't slip when tightened.
I did this on my 710 which has similar struts and brakes to the 510, using Maxima wagon struts which are almost exactly the same as the zx struts.
Maxima and 710 struts and brakes.
One additional thing I did was increase the damping to compliment the increased spring rate. To do this is easy, I just removed the gland nut.... thanks for picture.
and poured out the very thin watery hydraulic oil. (looks like 5 or 10W) I refilled the strut with 20w motorcycle fork oil which is high in rust inhibitors and anti foaming agents and also comes in a variety of different weights. The hardest part was holding upside down and pulling the strut rod out and pushing in to dispel any bubbles when bleeding them. Leave a 1/2" of space at the top for heat expansion.
$3.50............ metal cutting blade
$20............... two two inch split collars
$17............... 1 liter of 20W BellRay fork oil. Enough for three struts. (you can use $5 a gallon hydraulic jack oil or Auto trans fluid too)
Total about $50
Not as easy as $350-$1,200 coil overs to adjust, but hey, once you get the ride height you want how many times a week you going to adjust it anyway???????
edit: I see it's for a 210 so just sub 210 where it says 510. One coil removed from the 710 increases the spring rate from 100 to 150 lbs per inch or about 50%. I don't know what the 210 rate would be