Paul, dear friends,
I am surprised that the unmounted B3 filter cards from Franco are so poorly utilized and perceived by customers as mysterious or impractical.
I gladly share my own component values and design methods. I have two custom HF cards for the 60 meter and 49 meter broadcast bands that fit nicely in the original card slots of my DUOr. My 60 meter card "works" while the 49 meter card is "pretty good" in my own terminology. :-)
I'm not on top of the situation when it comes to the other types of cards from ELAD, but regarding the B3, I am able to be very specific.
For illustration, I'm providing a list of my own embedded DUOr cards.
Position 4 FBP80-1 3.150.000 4.150.000
Position 6 Custom 49 meter 5.700.000 6.200.000
Position 7 FBP13/21 13.600.000 21.500.000
Position 8 FBP21/35 21.500.000 35.000.000
Position 9 FHP1M7-1 1.700.000 54.000.000
Position 10 FBPY(BYPASS) 0 1.700.000
All the best!