LS3/5A and Linn Kans are a bit on the bass-lite side for my tastes. The original version designed for the BBC was used for voice monitoring in radio broadcast suites, so the emphasis wasn't really about music reproduction.
B&W602 might be a bit low rent unless used as a test-bed project.
I'd be tempted to look at some of the better 6" and 8" dual concentric drivers from Tannoy. There are a couple of reasons for this. First, the drive units are bloody good, and being dual concentric means the issues of time aligning two individual drivers disappears. Second, there's a long history of mating Tannoy drivers with various cabinet designs. Plans for those cabinets might be available online, so you could get hold of something already proven to work. Next, the heyday of this split approach was the 50s, 60s and 70s when cabinet making materials were sold wood, ply and maybe chipboard. More modern materials such as MDF and HDF and Corian weren't available, nor were some of the damping materials. It would be interesting to see what differences they could make to cabinet rigidity and energy handling.
The other side bonus is that the drive units themselves will hold their value.
