Question about having 2 600w HPS lights

I'm going to buy 2 600W Hps lights with a lumatek ballast and want to know if there is a bulb that I can put in there ballast for Vegation or do I have to go Buy separate the 400W metal Halides. Idealy I would like to just use the 600W ballasts. Is this possible???? Thanks!

They make MH conversion bulbs for 600w. Thats what your looking for.

Conversion bulb!!