As it is storming badly here I have not left the house this holiday. Would like to work on my trike build but just not going out in it.
So now you know... if you are going to build a trike you WILL have to work out the front end geometry.
Now for the "trike" part.
Rear ends.
Converting a bike is a good way to go. I like motorcycle based trikes.
Most start with a shaft drive and put a straight axle from a small car with a hand made mounting swing arm.
Chains and belts are a bit more difficult primarily because it requires more custom parts instead of junk yard salvage.