Realistically there is no difference between 38 and 357 cases apart from one is slightly longer.
If you used a 38 special load in a 357 case the only difference will be about 25fps depending on barrel length and coa length.
I am using 3,8gns of BA10 in 357 brass with homecast 135gn rnfp. Most pleasant and decent accuracy to 50yds.
I used to use Vectan AS which was cheap as chips until it dried up. Moved over to Maxam CSB5 and using up BA10 left over from pistol days.
TBH any fast burning powder shotgun/pistol powder around 3.5gns will work for a target load in a 357 case.
I have used just about most of these types of powder over the past 40 years.