wheels are lighter and should fit the 1000 wheel is 6 inches, so stick with the 600/750 wheels if u want the same size., and i think 01-06 1k headers are mostly for the better exhaust choices, and it probably saves some weight too.
do a search for all this crap, im about to do the wheel swap and the cam swap on my bike (2000 750) and ive asked one person a question thru pm about a specific thing and thats it, because alllll the info is already been answered and addressed on here. just gotta search for it bro