RE: CVA Optima Powder/Bullet Combination
Many people report outstanding accuracy with the CVA Optima. Especially with a scope, which is a great advantage to shooting longer distances.
As for bullets, since you want to shoot long distances, I would look for a sabot that had good ballistics. Perhaps a 300 grain or 200 grain Shockwave is where I would look. I would start the loads with 100 grains of Pyrodex RS and see how it shoots. My CVA shoots Shockwaves really well. Actually it shoots a lot of things very well. My pet powder charge seems to be 90 grains in the CVA. Anything more or less and the accuracy falls off.
All you can do is try some of the bullets out there and see which ones will shoot well. Then work up a load and practice.