So a recap.
Now we know that there is no "ideal" rake.
Differences in rake will give a bike different characteristics.
Take a crotch rocket..... very steep forks, not much rake and also not much trail. Very very quick handling, twitchy, the sports car of the bike world. Exciting to drive and you have to pay attention and drive it all the time.
Then the long front chopper. Assuming it is built correct, not too heavy on the bars, slower to change direction, takes more input to make a change, lazy, forgiving, does not take constant attention to keep it in a straight line.
In general all the same traits when applied to a trike. Except a trike will not forgive large trail like a bike that leans.
Ok so now you have read the tech link and have a grasp on the general theory.
Put the rake on it however you like or want.
I dont like long rake and the long front ends that go with them. My personal choice based on how I want mine to perform. I am more of a middle of the road, I want the looks of rake but I want to keep it bit more quick handling but not a crotch rocket personal choice, make your personal choice based on what matters to you.
Then.....
Make the trail fit.
You have the angle you just have chosen.
As the diagram above shows, get the relationship of the neck angle to the front axle.
Now you know where the front axle must be.
Next is picking a front end that fits those dimensions.