B, sodium salt, but B as a free acid will work as well.

I don't use formalin, as stated elsewhere. I use glyoxal, but either work. Formalin is faster in some ways and slower in others depending on the situation. For glyoxal, in 10% gelatin, I take commercial glyoxal solution and dilute it to 10% by taking the original glyoxal (10ml) and adding it to 90 ml of water and then use 5 ml/100 grams of 10% gelatin. That will harden paper coatings within 4 - 8 hours and film coatings in 12 - 24 hours. Formalin works faster, but keeps hardening longer.

For formalin, use about 1/2 that and make sure for any aldehyde that the coating pH is between 5.5 and 6.5. If it goes lower, allow more time for hardening and if it goes higher it will probably set up before you can coat it.

I looked at the list at that URL and got dizzy. At quick glance none of these dyes will work. Look for cyanines or merocyanine dyes. The best dyes are charged heterocycles. Chain length determines the color of the dye. As you add more methylene groups between the two charged heterocycles, the wavelength of maximum sensitivity gets longer.

Tables of them are published in Mees and James along with names and structures. I hate to scan and upload from copyright material. I'll see what I can find that is not copyright.

As for doing this, you should be able to coat and test the raw emulsion repeatably before trying spectral sensitization, otherwise it will be difficult to determine the degree of success. Remember that spectral sensitization alters blue sensitivity and emulsion contrast.