just a quick point, which I'm sure that you will know, regardless of whether or not you fit the hydraulic linked brake, (personally, I would not, they never worked very well and I prefer the sidecar brake to be on a separate pedal), if you have a chair on you should definitely fit the sidecar rear brake lever arm (No.1), its function is to stop the 'boomerang' in the brake linkage flipping past centre and sticking there, which will lock your rear brake in position and needs the bike jacking up to reset it, it really isn't anything to do with the hydraulic brake.