I got the alternative fuel pump fitted today. I went looking for a Bosch 0580 314 068 pump but ended up with alternative OEM quality one from GSF (
www.gsfcarparts.com)
The GSF part number is 183VG0291 or 18386F, total cost £50.40. This pump is very slightly longer than the original BMW one, which means the pipe stub on the pump and the pipe stub it attaches to are about 6mm apart with the fuel pump in place. It's no problem, you just need to spray a little WD 40 in the little rubber connector pipe and slide it far enough out of the way to allow you to fit the pump, the slide it back. The upside was everything fitted properly, the rubber vibration damper, the sock filter and the wiring (no mods necessary). New fuel filter fitted at the same time, and I replaced all of those nasty rusty nuts on the access plate with brass ones, and nut covers to ensure, they don't end up seized again.
Bike started first time and the whine is gone to be replaced by and almost inaudible whirr.
Anyway pictures....
New pump in place
Old pump
Brass nuts
Nut Covers