From "the carb shop" info compilation; 2 possibilities when N96: with or without N95
1970 383 manual - E & B-body - w/o ECS & with "fresh air" (N96) orange HP engine 335hp
---------- Holley R4736-1A ---------- part number 3512 964; Carb code on broadcast = 64
1970 383 manual - E & B-body - with ECS (N95) & with "fresh air" (N96) orange HP engine 335hp
---------- Holley R4738-1A ---------- part number 3512 974; Carb code on broadcast = 74
Wouldn't hurt to have someone else confirm or deny this as I have no 1st-hand knowledge.
Mark