Yep R1150 r bars will fit. I liked them. The hand guards do need a little persuasion and some on here have a problem with bending things to fit but should you not be that type of 1200 wasser cooled uncool person, you should be fine!
I'm another who has fitted R1150 Rockster bars, they go straight on, with the added benefit that they have the holes etc for heated grip wiring. As has already been mentioned the handguards have to be adjusted to fit. Mine have been on for the last 6/7 years very pleased with them.