I did hear back from Alliant, they say they have no internal data, and provided Lyman 49th for me.
Interesting info about the saami situation, if so, I agree that is the reason for the lack of data.
Quick, I may take you up on that. I need to order some brass, then the reamer. I will probably be using 777 for starters with the cases and eventually get some heavier than 300gr jacketed bullets to play around with smokeless. I do hope that I am still happy with my 45-70 performance after the conversion.
Where is wild west guns 457 data available, new to me. I was hoping Hodgdon would have some thing to add using H4895, since they use this for their youth loads. using this powder as a light load 458winmag would seem to be a candidate that translates to the 45-90.