I have found Accurate Arms #5 to be a good substitute for Unique .
For a faster powder more like Bullseye Accurate Arms #2 can be used .

I also found no Unique on the shelves but Discovered one dealer with a good supply of Accurate (Western ) powders. #5 works well and is accurate ....I am likeing it a lot !
Accurate powders are listed in the Lyman Cast Bullet Handbook and Accurate has a good amount of data on their site.
Gary