Well, they've still got plenty of time in veg to play around with them. I would definitely top it. Try putting a few stakes on either side of the plant or just attache a 2x2 horizontally to the fence behind it at 3/4 of the plant's height and screw in a few hooks, then start training the branches and new growth on both sides to run along the board. Grass is so resilient. In the meantime, take your cutting and find out what you've got. Good luck man, sounds like you've got a monster on your hands. And be sure to post some eyecandy.