Try AdventureTech, USA. This is their field, and I've had one of their lightbars (plus a wiring loom, etc) for a pair of front LEDs. High quality - reasonable prices... I hasten to add the one I purchased wasn't for an R, but they may well have one that suits.
Lawrence of Suburbia ('39 model) - living blissfully by the sea in Redland Bay, near Brisbane, Queensland, Australia.
Gone but not forgotten - 4 x GSs, 5 x cam-head Rs, 1 x F800 GT, 1 x LC R.