Dura Ace cogs and lock-rings are pretty solid, but I think their cogs only go up to 16t. If you want something bigger, I've had good (and inexpensive) experiences with Soma and All-City cogs (running an All-City 17t right now actually).
Disclaimer- I've never ridden or inspected a Kilo, so I have no idea whether that stuff actually needs to be replaced.