Joe, I have done 2 PDS swingarm conversions in my builds and they both work great for the reasons you mentioned. Simple, easy to install, components are readily available and since they are offered in much heavier bikes, it's easy to get springs from 690/950 bikes that will work on your project. For the FZ1 where I ran a 950 swinger and shock, I was constrained by the airbox, leaving my with a shock just slightly canted forward. I scrapped the airbox and went to pod filters and that allowed me to get the angle that looked "right". I then removed the spring from the shock, lost the nitrogen charge and cycled the swingarm to make sure that the swingarm with wheel went through the full stroke and that the shock also did the same. That ratio helped me place the shock in the right place and I welded it down. I left it tacked in while I was running tests and communicating with my tuner. His advice was to get the rake you want with the front end first. Easy, I duplicated a 950 SE geometry. So I installed the front end completely with wheel and used a floor jack to lift the rear of the bike until my magnetic angle gauge on the forks read 27 degrees or whatever the angle was I forget. I then build my scaffolding for the rear shock mount, tacked it in and dropped the bike on its weight. Invariably something would be off slightly, so it was back up in the air etc. One of the guesses I got very close to my geometry angles. Now the rear of that bike the swingarm pivot is higher than the 950 so I was heading into uncharted territory. At some point, you have to be happy with good enough. I'm not some A level rider and I don't want to bang my head on the wall that it was off by half a degree etc, I just wanted to ride. So anyways after all that, I rolled the bike out of the garage for its maiden voyage and have done 7000 miles since then and the bike has worked great. everyone who has ridden it never comments on that half a degree. Honestly for much of that build, and the one I'm building now, I rely on my eyes, hands and common sense. That might now be good enough for MotoGP, but my goal is to actually finish my projects and get a rider. Too many builds stall out because people either get mired down in the minutiae or lose focus. I think your plan for a new frame is excellent as well as the PDS shock setup. Hands down the easiest to get right. A linkage might be better, but its a 650 heavy bastard to begin with right?? I have a few KTM PDS shocks from an 03 to 08's if you can't find something locally for a reasonable amount.