You will need to make several changes to the frame
Currently your rear subframe is bossed and strengthened considerably as all of the absorbed energy from road undulations is transferred from your swingarm to the rear subframe, underneath your seat and tail section.
With a cantilever swingarm you will need a rear single shock mount point. You would need to build this and weld up your frame. If you are not well versed in frame technology and physics I would suggest you have this component created and installed by a professional frame craftsman. It would more than likely need to go where your current battery and air box are located.
Migration
You would need to migrate the location of your battery and perhaps even remove your airbox. If you remove your airbox you will need individual air cleaners for your carburetors. A re-jetting of your carburetors will also be in order if you do this.
You can get a small racing battery and put it in your tail section. You will be very unhappy with this small battery the first time you try and start your motorcycle more than a few times and it doesn't work. Get used to push starting your bike from time to time.
Swingarm
You will need a cantilever swingarm. If you do this, you may as well get a Honda SuperHawk single sided swingarm because, why not? Your biggest issue is going to be the mount point on the frame though, followed by aligning your chain properly and shimming your front sprocket appropriately and possibly cutting the downtube on the left side of the bike so the chain has clearance.
Big Project
Here is a summary
Remove the airbox
Get individual filters for carbs
Re-jet carbs
Migrate battery to tail section in order to have an open frame triangle without obstructions below the rider (it's cafe style)
Procure battery that fits into the tail section behind the brake/tail light
Rewire for new battery location
Modify frame for single shock
Procure new swing arm
Procure new shock to match
Re-valve shock for weight of rider and bike
Procure appropriate spring for shock
Modify sprocket alignment
Possibly cut downtube of left side of frame for chain clearance
Procure new rim to match swingarm
Procure new rear brake that will mount to swing arm
Procure new axle for new rim
Procure new rim
Make alignment spacers for proper rim fitment on axle
Procure new tire for new rim size
Procure new chain alignment adjusters to match swingarm
Procure or make new swingarm shaft to go through frame
Put appropriate bearings in swingarm to match new swingarm shaft
There you have it. That's a short list off the top of my head.
If there is a monoshock solution for your bike where you can take all the pieces off a different model and modify the frame it will make it much easier. You will still need to go through everything I've listed but if someone has done it before it certainly makes it quite a bit easier.
