The first bag is finished. While I’m not trying to turn this bike into an Interstate model, there are will be times when saddlebags are helpful. I don’t know if they ever made them in the Cosmo Black, the color of my bike. I’ve never seen any for sale.
I picked up a pair of saddlebags on eBay which looked like they might have been black — they weren’t — but which were so beat up it didn’t matter. The cases came without keys, but my local lock smith was able to quickly make keys using the code stamped on the locks. Unfortunately he couldn’t do what I really wanted which was to re-key the locks to my bikes ignition key. (Click on pictures to enlarge)
Here’s the left bag before painting. It doesn’t have as many scratches as the right bag, which is on the left in the picture above, but it had some cracks that needed repairing.
If you’re interested, I’ve created a separate page describing how I refurbished these bags.
When I bought the bike, I mistakenly thought it was ready for bags. It had crash bars and the latch tab at the passenger foot pegs. However, the bike required a couple of more modifications before the bags could be mounted.
The first item is the tail light extender shown in the next picture.
The extender mounts as shown with two 6×45 bolts and two 6×16 bolts. Before adding the bracket, the tail lights were mounted to flat tabs at the location now occupied by a fender washer and bolt. Unlike the tabs on the extender which are welded on, these tabs have a bolt and nut, allowing them to be removed. 
The second modification that needed to be performed was to lengthen the tail light wires. For that, I simply cut the wires and soldered in some extra wire. That way I kept the original connectors. I used heat shrink to cover both the solder joints and the entire length of wiring.
The mounting system on these bags seems overly complex, and heavy. If you’ve never used one of these, the bar with the “Press” button that looks like a seat belt fastener swings forward on a hinge and locks into place with the bit of hardware on the lower, left of the bag pictured below. When mounted it hooks into a tab on the passenger foot peg. The chrome mount in the center of the case (which is now black) fits over the bar that runs along the seat. The plastic mount on the far right fits over the rubber bumper on the tail light extender, and the rubber encased tab on the lower right of the case slips into the rectangular box on the lower part of the extender. The helmet lock arm then folds down over the plastic tab just to the right of center, preventing the bag from falling off, or being removed.
If you don’t have the extenders on your bike and you want to fit factory bags, find some. There’s really no easy way to mount factory bags without them.
Picture taken