Welcome to the Solex forum.
Some wheels are single crossed, others are double or even triple crossed. Also the shape of the rim may vary.
To be sure what is the right size, check it with a spoke length calculator.
Here's a handy tool to find out the right sizes.http://www.fietspunt.nl/spaaklengte-berekenen.html
All values must be filled in in millimeters
1. The hub: links (left); center; rechts (right)
2. The spokes:
Choose the number of crossings for the left and right side of the rim
3. The rim:
Inner diameter rim
Number of spokes
4. Press on "bereken mijn spaaklengte"
Note: for the thickness of te spoke, check the rim holes. The nipple must fit into the hole, but the nipple head must be large enough, so that the rim hole resist the spoke tension.