Before soaking the trimmed red decal -
Have a sheet of decal paper sprayed with gloss white paint. This will be used for the white edge. Spray a clear sheet with white getting full coverage.
Let dry thoroughly. No clear coat is needed on the white sheet, the white paint seals the surface.
You'll be making a composite decal, the red "1" set on the white base.
On the left is the two trimmed red "1"s.
You'll need tweezers to hold onto the decal when soaking.
Dip the decal for 15 seconds and remove from the water.
Change the position of the holding tweezers so the entire decal is soaked.
Use you rotary punch to get the upper left round edge cut.
This punch sets the thickness of the white border.
On the left is the trimmed decal with the new white border.
On the right is the second decal being trimmed.
Be sure your straightedge is perfectly positioned before cutting the white border.
You get one chance to get it right. Use a new blade.
I was surprised how well the red stayed on the white backing during the re-soaking. It didn't shift when sliding off the backing paper.
The "2" and "3" decals are wider than the "1".
It was set between the pencil lines.
And finally, the engine hook was scraped clean of paint and polished with some 400 grit.