plenty of room if he tops and trains the moms very young. ive seen 2' tall moms capable of 25-30 cuts at once. i would stay away from sativa dom strains tho as they grow very tall. i know gdp, bubba kush, cherry pie, purple kush, la confidential all stay very and bushy. querkle, plushberry and deep purple are all tga strains that stay short. if ur set on a sativa hybrid try vortex. it stays bushy and is amazingly unique. im not a tga fan but i know their strains lol and they win alot of awards. vortex is their only one i really enjoy but im not a huge indica fan either so maybe my advise is biased lol. id also advise a product called paclobutrazol. it is for use in bonsai trees but coincidentally keeps cannabis internodes very close so u get less vertical strech. id only use it after cloneing and stop a week before u wanna take clones so u can get a got chop spot.