Here is a description of the Miata front suspension and my measurements of key locations.
First some pictures I took.
Now my measurements. Done with a square and tape measure, so I am sure there is some error. I measured relative to the line shown in this image at X=2335. So an X value of -490 would mean that point is 490 mm behind that line. Y is positive to the right, Z positive up.
To calculate roll center we will also need the wheel and hub dimensions.
