Unique can be loaded in anything. I have used it for pistol loads, rifle loads, and shotgun shell loads. 12.0 gr of Unique under almost any cast lead bullet from 110 gr up to 180 gr in .308 Win is mighty versatile from small game to big game at short range.
I think IMR-4895 should be the other powder. Fair results in 223 and 308.
Your preperations you speak of is a good idea, but I hope you know that to really do this means...you better buy a couple moulds so you can cast boolits for your guns! You haven't over looked this aspect have you, hmmm?