No problem there. Just flip flop the A/V-3 plans.
I have had several builders do this. Many because they were going to have to be placed right up against a wall.
See side profile of the plans on page one.
http://www.gr-research.com/pdf/av3box.pdfYou have to delete brace "C".
Then move the drivers to the other side of the box (from the left side to the right side of the picture).
Then move the binding post to the other side of the box (from the right side to the left side of the picture).
Lastly, move brace "A" (the brace for the top panel) to the other side as well (from the right side to the left side of the picture).
That's it. Now you have the transmission line opening firing out the front. You can get real crafty and make a little grill for it to if you like.