I have all but given up on black patent due to the ash taste in my darker brews.
My last two stouts used only 2 oz of black patent and was fine. Anymore than that and I get the ash taste back.
One pound of chocolate might be a bit too much also, but let your taste be your guide and let us know how it comes out as you are the one drinking it and individual tastes vary.
How do you BBQ an elephant....first you get your elephant....