Welcome to the forum.
If you check with Cycles U.S. they have trike rear ends and a 3 speed hub. Also check with the sponsors ads on both sides of the form page to see if they sell trike rear ends.
For 26" rear wheels, www.worksmancycles.com
You will have to call and talk to them about the wheels since they have a hard to find price list. You can also try www.huskybicycles.com
Hope this helps.
Hard to find price lists???
Here it is... on the main page, put your mouse on "Home/Support" then "Downloads" There you can download the entire price list. Not so hard...