Sodium Metaborate, octahydrate (8H2O), and Balanced Alkali (Kodalk) are, for all practical purposes, the same. Substitution can be made weight for weight.
A substitution for sodium metaborate octahydrate is to use 9.5 grams of sodium hydroxide and 45.4 grams of borax decahydrated in water to make 1 liter. This is equivalent to 10% solution of sodium metaborate octahydrate. This can be made from Red Devil Lye and 20 Mule Team Borax and safely used in formulas as a substitute (20ml of a 10% solution = 2 grams; 25ml = 2.5 grams; etc.).