In that setup you are trying to grow 60 but you don't have room for huge root system.

I would go all 60 and start flower at about 8 inches. They double sometimes triple in hieght. Depends on the strain.

This method is to grow alot of small plants and cut down on trim foilage.

With you 1000 hps light you can get .5 grams per watt. So 500 grams and then the LED will help too. The right crop and conditions and you can get more.