CAUTION: The following post (or a page linked to) includes or discusses loading data not covered by currently published sources of tested data for this cartridge (QuickLOAD or Gordon's Reloading Tool data is not professionally tested). USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assumes any liability for any damage or injury resulting from the use of this information.
QuickLOAD thinks the starting load should be about 60 grains, working up to 66 grains maximum. However, QL sometimes underestimates pressure by a bit, so I would be inclined to start at 59 grains and think 65 may already be the upper limit. The problem is, this is for a case with 84 grains as-fired case water overflow capacity. If your cases have a couple of grains more water overflow capacity, that could change it back to the 60-grains to 66-grains range again.