Here are my guidelines for building:
1) Predominant riding terrain.
2) Primary rider's physique.
3) Lookup and read local legal requirements.
4) Type of bike.
Stay within these guidelines and you'll have a bike you can enjoy riding. Good luck with your build.
I strongly advice looking up and reading your local state laws before you buy any kit. Also with these kits you tend to get what you're willing to pay for.
Land Rider Jerry