As you stated, it's a WW2 era G46-8 by Western. The sheath is also WW2 era authentic. The G46-8 did not exist prior to about mid-1943. The pre-WW2 G46s came with 4", 5" and 6" blades with a mushroom shaped pommel.
The G46-8 was Western's response to not being awarded any contracts to produce the USN-MK2 or 1219C2.
An inch longer than the "official" Navy and Marine Corps knives, Western went with "bigger is better". It worked fairly well. The G46-8 was purchased by a significant number of units out of discretionary purchase funds. They were also sold through the PX/BX systems.
Your version is what many claim to be the first variety made due to the red fiber washers included in the handle and the abbreviated "PAT'D" stamp. Later versions lacked the red spacer and the full patent number was stamped into the ricasso.
This is the earliest version most folks are aware of, but it was not the first version.
The first, and rarest, version had the patent number stamped into the POMMEL. Not many of those were made. I have only seen 3 in the last 20 years. I have always thought that the pommel stamped versions were part of the initial "let's get these out to some units on the west coast and see if they fly" stage.