Would a speedlight 600 do the job? thanks

I went to a workshop with a photographer named Will Crockett. He does professional work in Chicago. This is a topic he discussed. I, however, do not own a Nikon so I did not take the info down. Look on the internet to see if you can contact him .

Whatever he says, do it because he is an expert in this topic. He also said some Nikon products don't work as well as other Nikon products do.

The SB-600 is an excellent flash unit. The SB-800 is even better, but it's really too much for me.

IMO the SB600 and the SK-6 Power Bracket would make a fine combination. Those extra batteries in the Power Bracket can really help with your recycle times.

Yes, good choice, but personally I'd go for a non-dedicated / multi-dedicated flash - a Metz - it's more flexible especially if you change your camera system at some time in future.