What was Winchester 785 powder designed to load?

Winchester 785 powder was designed as a slow burning powder for heavy bullets in magnum cases. It's burning rate is approximately the same as IMR-4831 and

H-450. Data for IMR-4831 would be a good starting point if you cannot find original Winchester 785 Data. Some older manuals such as Hornadys third edition shows 785 data for most of the common calibers.