Remember to look for Universal when you are looking for Unique as they are almost identical in use.
Looking at my loads table, I haven't tested Bullseye in the .44Mag. That is going to have to be 'rectified'!!!
. I've tested it in .44Spec with very good results, so I am sure it would work fine in the Magnum case too.
I've Tested 2400 from 16g (1116fps) to 20g (1333fps) in the .44Mag. That is one thing nice about 2400 is you can load it up and down. I standardized on 19.0g (1265g) under 240g SWC bullet as I felt it was the most accurate. 16g almost matches the 10g load of Unique. You'll need to test and see what works for you accuracy wise.