Jack,
'though am not Moz noa an LS User, what I've learned from the LS site is that every component (ie, wood used for cabinet, veneer, bolts, crossover components, speaker drivers) of the LS 3/5, under BBC standards, should be properly tuned, to maintain a linear frequency reponse throughout the entire listening bandwidth .
That's the reason why the crossover network for the LS 3/5 is very intricate.
Tried doing one a few years ago, when I got myself a pair of speakerlab woofers and tweeters similar to the B110 and T 27, respectively. never finished it