I design a helical spur gear with the following data:

The tooth angle is the following:

I need to create a worm gear that works with this helical gear that I designed. The worm gear that I need has five teeth and an external diameter of 26mm (I measure it with a calliper, but maybe it's not an exact measure). I don't have the resources to reverse engineering the worm gear, so I wonder if someone can help me to design (with formulas) the worm gear that matches the helical spur just created.