Carl, LS35A are not really a good option, because they need to be well out into the room for proper sound. For a similar sized speaker that is intended to be placed against the wall, you might consider Linn Kans. They are not high-efficiency either(I think about 88db), but at least will be placed right.
You should really have an efficiency of at least 92db for the 300B.
If you wanted to do some in-wall work, you could make a pair of single-driver Voigt Pipes built into the areas between 2 studs in your wall, and place the vents near the baseboard. That would require some wall tear-out and construction.
It's going to be hard to properly satisfy the requirements you have, without some serious drawbacks.
You should really have an efficiency of at least 92db for the 300B.
If you wanted to do some in-wall work, you could make a pair of single-driver Voigt Pipes built into the areas between 2 studs in your wall, and place the vents near the baseboard. That would require some wall tear-out and construction.
It's going to be hard to properly satisfy the requirements you have, without some serious drawbacks.