Hi Buck,
Wow your collection of classic rifles is still growing strong!

There was never any 80 grain Cordite load for the 450-400 3 1/4" NE.
The barrels are definitely both marked 60 grains not 80.

I see the description says the action is a PHV-1, but that is not correct.
The PHV-1 is a Webley design and is different in many ways to what is shown in the photos.

The action of this rifle looks similar to the trade actions which were used by many makers back then, but is not by Webley.

I bet you are keen to see how she shoots!
Please keep us informed.