How to rescale model

It’s not quite clear to me how to rescale the model. I have to calculate the dimensions manually because I don’t know the correct result measures. H

how to calculate them?

On the image I have selected the things I will scale. The second not selected is the map I am using for orientation. This is the goal size.

You see the selected image has a white space on the right.

My measures:
x1: 1999,608 (good size)
x2: 1243,4 (wrong size)
ratio: 1,608177578
xMax2: 1667,754
xMax2 correct: 2682,044588
There xMax2 correct is the size after rescaled x axis.
But I need to calculate this on z axis too. This is crazy!