As you say, the Sink pencils are undeniable. I see the hand of Manny Stallman is also at work here. I believe panel 4 on page 4 clearly shows the influence of Stallman.
Joe Simon is also represented here in the code-corrections. The man's head in panel 4 of page 3 is pure Simon. I must confess that as much as I love Manny Stallman's art, I don't think he and Sink make a good match. Still, their combined artwork produces a very interesting "atmosphere". I'd really like to see a copy of the published pre-Code story, to compare and contrast with this censored version!