Looking at it, I think the rifle is actually a transition block gun, with a pre-war safety. Winchester was using a lot of left-over pre-war parts during the transition time period. I've seen it all the way on guns made into 1952 and they're almost always H&H Caliber Rifles, but would need to confirm the serial number to be positive.
I personally have a .375 H&H with the prewar safety, prewar receiver bridge and bolt design, that is a Type II transition gun from the mid 1940's. I'm guessing everything on my gun was manufactured pre-war, and assembled shortly after WWII ended. Winchester made more guns in each of the years 1939 , 1940, and 1941 leading up to WWII, than they made in the entire 5 year period the US was involved in WWII.