Want to do Sog method but clones too big now? cut them to a foot or less?

Hey I got a few clones.
i want to do sog.. but a few are getting tall..
can i cut all my clothes to say about 8 to 12 inches then do sog?

Also how many plants can do Sog under one 600w bulb/ ballast.

thanks

How high is the celling and light?

light about 2 feet above clones or so...

Ceiling average height..

Why would you ever cut the growth?
If your worried about having enough height bend the plants over and throw a screen on them.