I would like to thank everyone who responded.

Picked up a nice Model 57 recently and kept my 58 NIB.

In the meantime I went with the recommended 7.0gr under a coated 215gr SWC.
This load worked beautifully - dead straight to point of aim and very accurate.
Not hot or mild - just right. Averaged a tad over 900 FPS consistently.

Appreciate the forum for all the great advice over the years. I am really going to enjoy giving this model 57 a workout and carrying it around the farm.