I don't have any saum data but the 6.5 Sherman has just a little more capacity. Here are some max loads for the Sherman which holds around two grains more.
65 Retumbo, 63 RL25, 60 RL22, 60 7828, 57 H4350, 63 H1000. These loads were developed with BR2 primers and 140 grain bergers. This might help you get started. Obviously, you should start well under these loads.......Rich