Yes, you can use KOSO and Dakota etc instrument clusters because your 2006 dual headlight model is NOT an dual headlight ABS Roadster despite many calling the 2004-2009 dual headlight Rocket III Standards/Classics and 'Tourer' marketing packages so. But they are NOT Roadsters which was the model designation for 2010 -2018 Rocket III's with ABS and CANBUS.
All the dual headlight models have 17" front and 16" rear wheels and a different frame to the single headlight models.
Completely different (but with same engine and radiator) are the SINGLE headlight, hard bagged, Rocket IIII Touring which 2008-2012 was without ABS but then ABS versions with same model name from 2013 - 2018 both with 16" wheels front and rear.