Yeah 1000 watt HPS should be sufficient, I don’t know if your using a tent or just free space? Mylar or foil the walls and that will help you keep light, however I have found HPS is not the best option for vegging and have issues with stretching. I run LED’s and then bust out the HPS for flowering. The down another downside on HPS is that they are directional and not full spectrum. Nothing wrong with HPS though! I for the first time will be using Spider farmer SF 1000 to flower this time around just out of curiosity of yield but pretty certain it will not produce them big dense nugs like HPS. Happy growing