Paint or photo editor works for design work. But for actual work make a cardboard template, by tracing the blade onto poster board. Now make your mods based on your paint model, then trace on to the actual blade with a black sharpie using the cardboard template.

You can make adjustments to your cardboard template until you are happy with the design and match the notch exactly if you want.

Fill in the part to be removed and the black will give you a good look of what it will look like on the actual blade. I usually make 3-4 templates before I am satisfied.

The heel will need correction, so this is a good time to match the heel shape to the toe shape. You want to move the corner of the edge well forward of the stabilizer. You may have to make adjustment to the toe curve to match the heel.

Cool project. bluing the blade would be cool.