The owner of the speakers had contacted Wharfedale, but
apparently the specs for these speakers were lost in a fire.
Looking on the net, I see other people have encountered the
same problem but nobody seems to know of a solution.

I would suggest this... Use the inductors and capacitors in the "common
sense" way I suggested, and measure the response of each driver pair
separately. This will give you an idea of whether you're headed in the right
direction.

Without knowing the impedances and responses of the "bare" drivers, there is
no rational way to determine what the crossover was. There is no magic
formula. One does not generally design crossovers without knowing the base
behavior of the drivers.

You will have to figure this out on your own. We can make suggestions for
starting points, but that's it.