I'm thinking you do as well as can be expected with a bank of floros. I use floros for cloning and veg with great success, and i even flowered under about your same wattage once with 4ft floro's, using a bank of sidelighting on each side, with decent results. A 70w hps will only cover about 1 sq foot with usable light. I bet you have a lot more sq footage to cover if using 4ft shoplites.

Another tip is that floros only provide useable light down a few inches from the bulb, so keep them very close to the tops, and dont expect much bud growth in the lower branches. Good luck