You're going to have to do a lot of trial and error to figure out how to fit your ECM, fusebox, horn and other miscellaneous wiring behind that windscreen going from an R to an S front end. The wiring set ups between the two models are totally different.
Do some google searching on "buell XBR to XBS front end conversions" before you proceed. It's not as simple as bolting on some brackets and a windscreen.
It can be done but it's not easy.
To change my set up from an R to a single headlight I actually swapped a complete S wire harness for my R harness.
The easiest conversion is S to R.
Not saying anything about your skill level or anything, just look into what others have done before you start buying parts.
Good luck