As I mention the 66-68 383 440 w/o A/C water pump pulley is the same as the one used on the hemi those years. Here is some information from an online ad for reproduction pulley those years.
66-68 426 Hemi Water Pump Pulley. New reproduction with the same spacing as the original. For use with original thick crank balancer or if using a crate motor must use spacer on crank pulley. Must also use a 64-66 or 67-71 hemi alternator spacer set (spacers are the same, but the housing brackets are different) and Hemi crank pulley. Pulley is painted black. Includes 4 - thin head self locking water pump bolts that are needed for pulley clearance (washers are not required). Replaces original Chrysler pulley part number 1821452. Also fits 66-71 383 and 440 without a/c. Will not work with 69-71 hemi crank pulleys.

The pulley diameter is 6-13/16" (almost 7 inches), depth from mounting to outside of pulley is 2-11/16".
Here is the same seller who also has the 69-71 Hemi water pump pulley. It is specific to the 426 hemi, nothing else and should be the correct one the OP is asking about, since he mentions 1970.
69-71 426 Hemi special water pump pulley. Only fits 69-71 426 Hemi. Same spacing as the original, for cars with or without power steering. Fits cars with original thick harmonic balancer or if a crate motor requires a spacer on the crank pulley. Must also have 66-71 hemi alternator spacers, double pulley alternator and 69-71 hemi crank pulley. The pulley is coated steel and should be painted black before installing.

Does not work with 66-68 hemi crank pulleys.

Reference Chrysler part number 2946716
Matt