I haven't used the RL powders as much so can't speak to that. Would still think if you see some load data for a similar bullet just start at lower levels and work up from there.
That was the plan. I wanted to make sure it seemed reasonable before I started. I'll post my results here once I get loads done and can get back from the range.
Out of curiosity, what's your favorite Hodgdon powder for your Weatherby loads?