It has all 10 out of ten differences to make it 461. Its on cover watermark not known. I might send it in. I have two alike same dates and same address, This one has lower left crease so ill likely send the other.
Here's a link to check out. Apparently, to be a 461, it needs a perforation of 11 on all sides. https://www.theswedishtiger.com/ID332.html