Light space for Sativa SoG?

I plan on growing a SoG of 2x Sativas after I get these vegging plants through flower. Should have recovered from December heating bill and Christmas by then.

Will be growing hydro dwc, packing 24 of them under 2x600w inline lights. I am planning on having the lights 3 feet away from the medium. I want them to stretch them almost to the light. Should I go farther up with the lights? I know Sativas stretch but I like them, and I plan on flipping them to flower about two weeks from seed.

If everything goes right I should have these strains:

http://www.worldwide-marijuana-seeds.com/products/nirvana-white-widow
http://www.worldwide-marijuana-seeds.com/products/barneys-farm-acapulco-gold

I need some input from SoG growers.

You want to give the sativas as much light intensity as possible to reduce stretching. 36" is too far IMO - they just won't be getting enough quality light.