Primers, being as to how ya haven't had any hits on your request, I'll see if I can help. If none of the powder companys have no loads in the data, at thier web sites, I do know that many times, on obsolete guns/ammo you can contact thier tech support and they will develop a load for your round.
Many times I have contacted Western Powders, in Miles City Mt., and they have developed loads for me, that gave me a starting point.
I do have 7 manuals with data for this round, however, 7 of these manuals are vintage Ideal, and the powders reccomended are no longer in use. The other 3 manuals to use current powder Ideal Handloaders manual 39th edition (1953), The Lyman Handbook of cast Bullets, (1958) and The Lyman Reloaders Handbook, 43rd edition(1965). These 3 manuals only have the same 3 loads, 1 for a 290gr. cast, a 300gr. cast, and a 300 gr. Jacketed.
If all else fails, drop me a line at email@example.com
,and I will send ya that data.