Good points from focusinprogress. Presumably, the intent here is to improve your motorcycle rather than simply change its appearance. That is quite a tall order compared to what at least visually seems like a fairly straight forward job. There are several areas to focus your attention on. The first is the kinematics involved, which is the relationship between the moving parts as they pass through the travel of the system. It is important to consider what the total travel of the swing arm will be. Generally you will need to reproduce the stock travel, both in degree orientation to the frame and the range of motion. That is due to the constraints of the chain drive - you can't change it substantially without incurring trouble, and this includes the static sag of the new suspension. Once this is determined, the shock location and orientation needs to be determined. This is driven by the angle it ultimately makes with a line drawn from its lower mount and the swing arm pivot point. The swing arm itself is in no way a factor here aside from whatever mechanical attachment and structure needs to be created to accommodate the desired location. This angle is the driver because as the suspension compresses, the angle the shock makes with the swing arm pivot changes and in doing so changes the rate at which the shock compresses which is critical in how the suspension behaves. Generally, the rate at which the shock compresses should increase and max out at full compression. How much, and how fast this should occur is worthy of a book, or at least a chapter or two. The idea is that small bumps should easily move the suspension, but the increasing rate will keep large bumps from overwhelming the system. This is easy enough to manifest, but aside from doing it all on paper (or a computer console) I can't imagine doing it without a bare frame and springless shock with which to mock up the system and run it through its range of motion to make sure it is all within reason. Since you are starting with an existing bike not intended for this arrangement, your decisions will be driven by the existing architecture and what you are willing to delete. Secondly, serious consideration must be made regarding the structure of the modifications, as has already been mentioned. The existing swing arm pivot is likely ok, despite the new loads being MUCH higher than with the dual shocks. Increased wear could be a problem, but I'd reckon there is no actual safety issue. Whether or not the increased loads will create generally undesirable flexing in the chassis creating durability or driving issues is hard to say. The important thing to realize is that the loads on the shock mounts are VERY high, and spreading them out into both the arm and the frame appropriately is critical to avoid localized failure. This is not the same thing as reinforcing the frame and arm to keep flexing at bay. You could triangulate the frame to make it plenty stiff, but still have the actual mount fail if it isn't engineered sufficiently. Finally, the sub frame supporting the rider needs some consideration. Where with the twin shocks, that weight was substantially transmitted directly to the ground via the shocks and wheel, now the entire load must be transmitted back into the frame and then into the rest of the chassis before reaching the ground. Much of course depends on the riders position here, but I'm assuming this is a street bike where the rider actually sits a great deal of the time. Again, it's good to do an actual full motion mock up to see if everything works before you carve things into stone. Looks like your hoop will become a brake at full compression. Designing the sub frame is simple compared to the suspension, so finalize the hard stuff first.