The Ramshot data shows 7 to start then 7.9 max with a 125 grain jacketed bullet. Since the 7 matches the data you cross referenced, that is a reasonable place to start. You can also reference 38spcl +p loads with the same powder & bullet. Yes it will be much less, but is an idea of a lower floor you can factor in if you want to keep loads modest.
Depending on the gun & all, I'm not a big fan of 125 grain max warp loads in a 357 mag. Even the starting loads will be much more than a 38sp +P loads. In a snubbie, I may hang out in the middle somewhere.
There are controllability issues, muzzle blast, and potential erosion problems.