Norma has data on their site: http://www.norma.cc/en/Ammunition-Academy/Loading-Data/

I use Reloader 19 in my F. Kettner. The load is from a German RWS manual, "Wiederladen" that Old Western Scrounger sold in the past. Some of the RWS, Norma and Reloader series powders are interchangeable. For instance, it is my understanding that Norma 204 is or was Reloader 19 and Norma MRP is or was Reloader 22. I WILL NOT STAND BEHIND THIS LAST STATEMENT. Please do your own research before attempting any powder substitutions!

Hornady does have data, with a note to reduce loads when used in break open guns. 7x65 R is a lower pressure version of the 7x64 which is almost identical to the 280 Remington. Combinations that work in these 2 cartridges would be interesting to review for background comparison only, as they would almost certainly be of too high pressure.

Feel free to PM me for more discussion.

Good Luck.