You have 84 square Ft. You need 5000 lumen's per square foot (That is said to be the growers minimum to Flower). 1000W HPS gives out 130k lumen's - 140k lumen's per square foot.
84 x 5000 = 420,000 Lumen's
You would need 3 1000w Hps lights in there if my math is right.
3 x 130 = 390
3 x 140 = 420
Depends on the type of bulb and ballast. lumen's go down after some use, so you will probably need a 600w backing them up to keep you above the 5000 lumen mark
You would probably want to split the room in two, a flowering and veg room. Would save you a little on electric that way.