Ron informed me that there was a thread about trying to find some red sensitizing dyes. Although I've not started messing around with any color sensitizing dyes myself yet, I do come across a lot of information regarding it. Attached is an excellent list of sensitizers from Hans Bjelkhagen's Silver Halide Recording Materials: For Holography and Their Processing. I'd consider this list an authoritative survey of the currently available sensitizing dyes.
Unfortunately it doesn't say which spectral region they sensitize for, but this information has been hashed out ad nauseum in historic literature. I was recently amazed at how many articles I found in British Journals of Photography, 1900-1918, that discuss red sensitization and the like. Has anyone considered bath sensitization?
Here's an interesting snippet from Bjelkhagen's book... "The particular sensitizing dyes mentioned above [below] and their combinations were discovered and used by H. Lehmann to produce the best correct-color sensitivity ever achieved in Lippmann photography. However, he kept secret his good formula for Lippmann plates and it was not revealed until after his death. If one wants to try this old photographic technique today, these dyes are definitely the first choice."
Those dyes are:
Pinacyanol ----- 1:1000 [chloride, I presume]
Orthochrom T -- 1:1000
Acridine orange - 1:500
I think this would be an excellent trio to work with as an amateur emulsion maker.
Best wishes y'all!