Sounds like you are on the right track. I have had good results with that bullet and 800-X. Better results with Accurate no. 9. Carefully working up a load of A9 gets good performance at 1205 fps from my stock G20 barrel. I used a CCI 350 for the A9 load. I can't say that I can share any Longshot first hand experience with that particular bullet though. Glad to hear that they bullet is feeding well in your LW barrel.
This bullet is my favorite for wilderness carry.