Always follow your manual religiously and use cast bullets. The .38 S&W uses a .354" to .360" bullet. .357" cast will be fine.
My old Lyman manual gives Bullseye for the accuracy load for a 150 grain cast bullet. 2.0 to 2.9 grains. This data will do nicely for a 148 grain bullet too.
For a 158 grain cast, 1.8 to 2.5 of Bullseye.