http://www.troelsgravesen.dk/B&W-802s3_Upgrade.htm
These speakers, like a number of Infinity and some Focals I’ve personally measured, are good candidates for a crossover redesign as opposed to 1:1 parts replacements. I’d avoid doing parts swapping for the sake of doing part swapping.
I'm not sure why the link above isn't working correctly, but try going from here:
http://www.troelsgravesen.dk/Diy_Loudspeaker_Projects.htm#PAGE_INDEX