Kevin, with good bullet fit, & that usually means a .430"-.431" cast bullet, your gun will shoot just about any combination you can load up. Using the Unique you mention, which is one of my 45 year favorites, you can use the Skeeter Skelton load of 7.5 grs Unique & a 240-250 gr cast slug in 44 special brass. This load usually runs around 925-1000 fps, depending on barrel length, I've taken several deer with this load. Using the lighter 200 gr bullets you can start at 7.5 grs Unique & work up until you find a sweet spot.
Some will tell you that Unique is dirty....guess what, its dirty, its also one of the very best powders out there. If your gun gets dirty you clean it, thats kind of the way it works! If you don't want it to get dirty then don't shoot it.
Using 44 magnum brass you can start at about 8.5 grs of Unique & easily go up to 10 grs using the 240-250 gr cast slugs. Again, with the lighter 200 gr slugs start at 8.5 grs & slowly work your way up. The 10 gr load with 240-250 gr slugs will usually run right around 1100-1150 fps, depending on barrel length, cylinder gap, etc. My everyday, all summer load is, 8.5 grs of Unique using a 250 gr Keith slug in 44 magnum brass. Enjoy your new gun.
Dick