Are you going to use Magnum brass or hotrod Specials?
In .357 Magnum brass, when I was shooting USPSA Revolver, I got a 158 cast roundnose in a 4" M28 as follows:
8.1 gr Blue Dot = 1138 fps f = 179,804
(Major was 175 back then.)
6.7 gr Unique = 1075 fps; f = 169,850
6.3 gr Win 231 = 1050 fps; f = 165,900
(Too light for USPSA then, fine for that or ESR now.)
I don't know why I got by with lighter loads than Paw Paw, but there it is.
There has been some work done in recent years on recreating the .38-44 High Velocity which would let you use .38 Special brass which is cheaper and ejects .135" quicker.