Never the less, 777 formula from unblinkingeye works great for me on HP5+. I used N,N-Diethyl-Phenylendiamin-Sulfat from Merck in that formula, it is a fine slightly off-white powder. Just the Glycine is very expensive....

Thru the years I used a fake formula of Calbe A 49, which turned to be a fake formula of May&Baker Promicrol and it still works well with 400 speed films, using
6 g N,N-Diethyl-Phenylendiamin, 1.2 g Glycine, 100 g Na-sulfite, 12 g Na-Carbonat
The combination Phenylendiamin/Glycin seems to reduce grainsize on old style emulsions to improve resolution.