homemade honda fat cat. this is a definate future project for me. i already have 2 200S 3 wheelers one going back stock so the other can be converted like yours. i will be keeping an eye out for a BW swingarm or i will just have to make my own! i would like to build a pro-link setup on mine!
The 200S is a good choice because the front forks are the good hydraulic type shocks and the width takes the narrower 11" tires.
I went with the old 200E BR because I wanted the H/L range tranny for the mountains, plus I had one laying around minus the front end. I used 200S front forks extended 3" for better steering and handling.
The rear suspension is pretty stiff, a mono would be nice. Maybe a 200X trike would be a good option , you could easily modify that swingarm. I would like to get away from the jackshaft BW swingarm but the only other option is to build out the front sprocket with some kind of adapter or extension so the chain clears the tire.
I have seen Honda 200x bike mods and they run narrower tires in the rear (probably 8-9") with what looked like custom built swingarms with no jackshafts. . All good fun!