G'day Mark,
The frame and engine numbers you quote are correct for a 1945 - 1947 Ariel 350 cc as per the literature I have. It doesn't differentiate the years. However, given that we were still at war in 1945 it is unlikely your redhunter is from this year as they were still making WNG's or the military version of the 350 at this time.
If your bike has girders, and I think it has from memory, then it is a '46 as they went to the "new"tele forks sometime in '46.
I hope you are bringing your Ariel to the annual Ariel register rally at Euroa, Vic on 29/4 to 1/5 2011 although it would be a long journey from WA!
Cheers,
John.