Hodgdon has some very nice loads posted for the 45 LC using Lil'Gun, but they are very fast generating 25,000 to 29,000 CUP. However, it is a great powder for reduced loads and has the same burn rate as H110 and W296, both of which have ignition problems with reduced loads.
The start load for this powder with 260 gr Nosler partitions is 19.0 grs for 1196 fps and 24,500 CUP, so i figure you could drop to 16.0 grs and see if you get 900 to 950 fps.
Working with reduced loads in the 454 Casull, I found Hodgdon's Longshot to be very good - slower than Blue dot and 800X, but faster than 2400.
With the 4.625 inch bbl, don't overlook Bullseye, either. Only 5.4 grs will drive a 250 gr lead bullet 805 fps at 11,800 CUP, so there is room to work up from there in the strong Ruger. This powder is 40% nitro and loves big, empty cases giving very uniform velocities. You should be able to make 950 fps with a 255 gr LGC with very little recoil and a high accuracy potential. Nothing wrong with 1000 rounds per pound either.