Thoughts on Swapping 2 x 600w for 1 x 1000w

Ok so i was thinking of swapping my 2 x 600w hps lights for a 1000w i have lying around. the main reason for this is just to try and cut down on heat and save a lil money on electric. The hud on the lamp is pathetically small tho especially since its 1000w. To rememdy the poor spread of light from the shader, im going to buy a new one which is about the size of the 2 hoods of my 600watt's put together roughly 4ft x 4ft, now the main problem im coming across is finding a 1000w hps bulb that mediates between vegetation and flowering evenly for a fair price. i received the light from my gfs aunt so im not to keen on using the bulb it comes with, i mean i dont even know which type of bulb it is, so if anyone can point me in the right direction or even enlighten me as to recognise certain bulb types it would be much appreciated.

grow space: 7ft x 6ft
# of plants: 15
breed: jamaican ice

you will get a much better yield with 2 600's at only a little bit more power. 200 watts. plus you dont have to buy a hood. The money you save on not buying a new hood will more than cover the electricity difference. So will the extra yield. And i doubt there will be much difference in heat.