Since Forte has gone, Fomatone is my favoured lith-paper if color is desired. With much light, strong developer-dilution and long development-time, we get very colored midtones and lights, but no really deep black.
I see three possibilities to solve this problem:
1. thin man and fat man in the bathtub
Exposure + 3 stops 7 minutes in the thin man´s tub, 1 minute in fat man´s tub
plus 1-3 minutes selenium-shower
Disadvantage: Dilutions of 1+30 or 1+40 are not stable