Metalrat, a couple of things to keep in mind on that "Improved" 25-20
32-20 and 25-20 brass is relatively thin. Watch for pressure signs at the base, near the rim when loading things upward.
32-20 brass necked down to 25-20 will have a thicker neck than was originally intended. This almost never causes a problem, unless your brass stretches out to an interference fit in the chamber. Rare, but it has happened twice that I'm aware of.
There is still some old 32-20 and 25-20 brass floating about that is balloon head. If you are using only new brass, you are just fine. If buying from an unknown source, check the heads carefully. The balloon heads will not take modern pressures. They were intended only for the black powder loads.
Last item: Welcome to the forum.