how to scale them so they ALL display as 1:1!
After "inserting" the viewport ... Select it, then R/Mouse click / Viewport properties
You will see a box that you can "Check" (tick) for fixed scale
Check (tick) the box and then the "greyed out" scale box springs to life ... select your fixed scale and close the window .... Now select your viewport and adjust (pull) the edges of the "viewport window" so that you can see your "View"