0.75g/w would probably be a decent gues i think? it comes down a lot to what strain you grow but you have some nice topping/lst going on there so id say at least. i dont think you will hade a problem getting a QP. my first grow ever was in a DR90 with 1000w growing 20 autos in 3.6l pots and i got 437g.
Like i said i think you will do just fine. your plants health tells me so