Ok... so as long as the trail is good just about anything is rideable. You may want more or less rake or more or less neck height for your specific purpose.
For instance a crotch rocket has a low neck and little rake. It handles quick and nimble but can also be quite twitchy at high speed. Not really a beginner bike.
Then at the other extreme is a cruiser, long slower to turn, very stable and straight ahead at speed. Blow down the highway with very little rider input.
When I build I do it to my personal preference. I have an idea what I want it to look like and what I want to do with it. My tricycle is 40 degree out from vertical ( some rake but not so much). The neck is low ( i can measure it if you want). And the forks are short and stiff. So basically mine is a sporty run about not a highway cruiser.
Look around and get an idea of what you want it to look like, what will fit your body type, and the purpose you intend for the bike.
You can make the numbers work for just about anything, the basic geometry is the same for all the suspension types. With a girder or a spirder the dynamics of what happens during the travel will need to be considered. For instance does the trail get longer or shorter as the suspension moves.
Do you need info on how to build a girder?