smart Skyline,
Presuming you wish to enlarge the map, you can do it like the third way described above without calculations as follows, Smart Guides being your friends telling you when you are within snapping distance.
It is recommended to keep backups of each step to fall back on.
1) Zoom in so that the scale from 0 to 1440 km fills much of the screen, then with the Line Segment Tool ShiftClickDrag at the bottom of the scale from 0 to 1440 (this is how much 1440 km corresponds to in your chosen unit);
2) Choose how many units you wish the 1440 km to correspond to (presuming this is a larger number);
3) Select the line from 1), then Ctrl/Cmd+C+B (hold Ctrl/Cmd and press C then press B) to create a copy behind it, then click the leftmost Reference Point in the Transform palette, then click the value in the W box and change it to the number of units you chose in 2), then change the colour to red; now you can see the rightmost part of the red line exending past the original one from 1);
4) Click to select the line from 1) and switch to the Scale Tool, then Click at the left end Anchor Point to set it as the key point, then ClickDrag the right end Anchor Point along the extended red line (Smart Guides will say path) until you are within snapping distance of the end of the red line (Smart Guides will say anchor); now you have set the scale you need for the next step;
5) Select the map, then open the Object dropdown: Object>Transform>Scale, then click the Non-Uniform Horizontal scale value (in %) and Ctrl/Cmd+C to copy it, then ClickDrag over the Uniform Scale (in %) and Ctrl/Cmd+V to replace it by the new scale and click OK; this will scale the map up to the desired size. You can ClickDrag the 0 - 1440 km scale to check.
I have included sketches below to give an impression, following the steps.
If something goes wrong, please show screenshots of the steps as described below, and explain.
Unknown to most, it is quite easy to directly show images in posts, hence the following general suggestion:
Please show images by using the Insert Photos button (looks like moon over mountains) for each at the top of the reply box which makes everything appear right there in your post together with your text, rather than he more conspicuous Drag&drop attachment which requires helpers to open a new tab for each image and wait for its showing, then go back and forth; and if they just click it and wait for its showing and press the X to get back to the text, the image is gone so they have to open it again and wait to see it again.
Click to get closer, Click again to get closer still
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