These are the numbers I get measuring along the underside of the spring with the tape measure end hooked over the center bolt:
530mm center bolt to middle of front eye
650mm center bolt to middle of rear leaf eye

That adds up to a bit longer than the listed spec because the tape measure is hooked over the center bolt and the tape could not be right against the spring because of the base plate. Plus the error in judging the center of the spring eyes. But it's close enough for these purposes.