Hi gundog
I have used 73.0gns AR2208 behind 410gn Woodleighs as a working load in my .416 Taylor for years (2340fps). I also used 76.0gns behind the 340gn Woodleigh, this is somewhat milder load than the 410gn load (2500fps). Please be aware this data is ten years old.

I know the cartridge is different however they seem to be very similar!