Actually, I think "the Load" was dealing almost exclusively with .38 Special loads using SR 4756.
This is data from the 2nd edition, 1971, of Speer #8. It is normally an accepted practice to use the data for a heavier bullet of the same material/construction with a lighter bullet.
I would start low and work my way up, especially if I hadn't been using SR 4756 loads in my gun. Maybe something more along the lines of this DuPont data.