Do a search fella and there's loads about Mille's being over geared :thumbup. Certainly dropping one tooth on the front is a must, then go 2 teeth up on the rear. New shape RSVR's and Factory's have a chain length compatible with this, old shape RSV Mille and Mille R need a 110 link chain unless the old chain has stretched enough
Old shape 1998 to 2003.5 RSV Mille and Mille R standard gearing is 17/42.
New Shape 2003.5 to 2008 RSVR 1000 and Factory standard gearing is 16/40