Final answer:
The choice d. 'Belly cleaned substantially of all fat' is not a typical specification for custom cut NY Strips, as the belly is typically not part of the NY Strip cut.
Step-by-step explanation:
Among the specifications for custom cut NY Strips in the question, d. Belly cleaned substantially of all fat is not a typical specification. When custom cutting NY Strips, it is common to trim the fat cap to 1/4", ensure that the tail does not exceed 2", and it is acceptable to have a vein on one side. However, it is not standard practice to clean the belly substantially of all fat because NY Strips are not typically served with any portion of the belly attached; the belly would be a part of a different cut of meat.