The Agfa paper did not have an ivory base. It was a warm-tone paper with a warm-tone base. It is not a very good idea to put a warm tone emulsion on a neutral white paper. It would look weird.
If you compare the paper base of Ilford's (or Kentmere's) warmtone paper, it is much "warmer" than the base Agfa used. The particular charm of Agfa was that it was a warmtone emulsion on a more-or-less neutral white base. The base may not have been a brilliant white, but it was definitely a cooler tone than the emulsion. It's this combination that I've been unable to find anywhere.
I think, for example, that Ilford could coat their warmtone emulsion (which I love) onto a paper base that they are currently using, e.g., Galerie or MGFB, and the combo would approximate the warm/cool look of the late-lamented Agfa.
The chloro-bromide emulsions always give better shadow detail than the colder-toned emulsions. When I compare a print of the same neg made on (for example) Ilford MGFB with one made on Agfa MCC or even Ilford Warmtone, the difference in shadow detail is astonishing. On the warmer toned emulsions, you can see all the way into the shadows with great tonal gradation. In the colder emulsions, you can't. Yet, not all subjects lend themselves to the ivory/yellowish look of most of the warmtone papers out there, a look that is principally due to the ivory colored base.
Larry