The Brovira and Portriga formulas were very close together. They both used bromide, chloride and iodide in making a simple emulsion. The big difference seems to have been the curve shape, as the tones of the two silver images would be very similar. This would place both of them in the same category of Kodabromide paper from Kodak.
I think that any AgCl/Br/I emulsion would probably give similar results unless there is an additional something in the way they added an overcoat, or a special support they used.
Agfa coated on schoeller baryta support. It may have been specially tinted and may have had a special overcoat.
Good luck finding your dream paper.