Benzotriazole is usually used as a 1% solution and potassium bromide as a 10% solution. Usually the same amount of solution is used whether BZT or KBr. I don't know where Anchell gets his figure of 0.2 g of BZT. In general I am rather skeptical of Anchel's book. I would suggest making up Ansco 130 without either chemical and then adding small amounts of each until you obtain the image tone you are seeking. I have done this myself with another paper developer to get a purely neutral black which I favor.
A 1% solution of BZT is easy to make without resorting to any other chemicals. But you need to start with hot water or else do a lot of shaking.
The amount of resttainer is dependent on the paper used. What is listed in formulas is a compromise vaule which may not be ideal for the paper you are using.