Start out using the lead loading data on the Hodgdon website. With several mfg lead bullets I have had great success using Universal with HBWC. I typically count on 3.1 to 3.3 grains to give me easy shooting accurate .38 rounds like this. I do not load straight lead in 357. But Im sure you can find a low end load for the plated bullets you have.
http://data.hodgdon.com/main_menu.asp