doing large grow with T12's 4' only any one here ever do this and how id it turn out?

im doing a large grow in my basement soon. wanted to know how manys T12's you used? and how you set your grow room up? i have the room to grow 30-40 plants if i want. im using T12's becuase im getting the fixtures for free and the bulbs are cheap. im using 6500K for veg and 3000K for flowering. thanks for all your help in advance. good luck with ur grow every one.