Great so now what you roughly hear/feel on the 8340/8340 shouldn't be too far off with what I hear/feel here with my 8330mkII.
Best keep the 8340 as matched for overhead so tonal timber balance of the frequency is the but the 8320 should come in very close with a little manual 1/3 EQ.
You really do need at least a good 3 8340 per side wall spaced out to create the defused refocused "surround" a pair or one each sidewall to my trained ears just won't cut it. which is why I got as many as I can get my hands on.
Get another pair 8340 cheaply if you can? But the 8330 are great and often sell ultra cheap on eBaY and maybe be a bit heavier to put up as the plastic boxes have reduced weight.
Get the pictures up when you get the 8340/8320.
Place the first set of 8340 behind any second row seating! At equal height and maybe a little lower down so they are not too close to the ceiling but with mine I had little choice of options due to 7'8" ceiling, otherwise when fitted x3 per sidewall will give impression of HEIGHT SURROUND.
Reason for placing first set of 8340 behind any back row seating is so that back row gets impression of "its behind you" if placed too forwards it will sound like its beside you.
Once you fit a second row in and play an "all-channel pink noise" only on the sidewall surround, you'll grasp the idea.
keep the second row a few inches behind any front row seating.
Place a third row so its a in front and at roughly same spacing distance and once all x6 are set up the sound of surround will wrap around the seating, just like the cinema.