I think you should be okay. The 802d puts out a whole lot more bass than your 803s. You will love it. I had them both. You need a Krell amp to get the best out of your speakers though. I use a 700cx.
You should be fine. I have the 802Ds and a similar sized room with an opening to a dining room and hallway. My room is 15'x27' with 8 foot ceilings.
I end up with a room node from 20hz-30hz due o the length of the room. Even 703s did that though. It is managable though.
Start with the 802Ds ~20" from the side walls, and ~24" from the fronts wall. Give this a listen. If it sounds boomy, then pull the speakers out a little bit more from the walls.
the room size should be OK.
you may want to pull the speakers out as far as you can. First, it will most likely sound less boomy, and second, you will increase soundstage depth. The closer the speakers are to the wall behind them, the less is depth of stage, unless you got some serious room treatment on that wall. But chances are, you may still need some sort of bass traps behind the speakers. What kind of amp? What power?
you'll need to experiment with speaker placement and possibly with bass traps. There may be some suckout on the left side due to the openning into the kitchen/foyer, which will also cause you to play with speaker positioning to achieve proper center fill and soundstage. You'll figure it out as you start setting it all up. Play it by ear.