I can't find that (at least not legible) on any of the copies of 66-67 Chevelle B/S's I have.
But that pulley # is listed in the 67 Chevelle/Vair/Nova parts book, and in the 66 Psgr/Vette/Truck book, as fitting:
65 Nova 4-cyl
65-66 Nova 8-cyl
66-67 Chevelle w/ 396 (exc. L78)
65-66 Passenger 8-cyl (exc. 409 and 396)
Don't know if 67 and later full size used the same pulley or not.
Does it have a cap on the pump, or is it set up for a hose to a remote resevoir? If it has a cap then you can strike the Chevelles off the list above. If it is for a remote resevoir, then it should be for the 66-67 big block Chevelle.