Careful with brackets- it has to fit the curve of the block and the water jacket bump. Since you're not running Motronic , you don't have to worry about grinding to fit the crank sensor.
If your factory bracket is good meaning the isolating rubber bushes ; there's nothing wrong with it. I rebuilt mine using 1/2" pvc pipe and a couple of brass/ nylon bushes from the Depot.
As far as compressors, the 508 is tried and true. But as far as looking factory- BMW used Bosch for a period after York. The 508 is a wobble plate design where now or recently full rotary designs are available supposedly even more efficient. As far I know, Sandens are Chinese made now according to what I read a year ago or so. That's why they're cheap now.