I hope you have enough room to trim them up.
Do you have screws to assemble it for testing?
You can always use paper clips inn a pinch.
They are about the right size.
I would take one scale put some masking tape on the inside and put the blade in it, then mark where the blade goes to.
Then take your other scale, place it on top and see if you can trim it up with the distance you have set already.
Sounds complicated, but it's easy to see that way.