A DC Lee mould in .350" or .355" will do just fine.
I am using an old DC RCBS mould I had stored away. I would much rather use a .355" RB mould, so will have to buy/order one.
I tried to use Hornady 0 buckshot (I think it was) in my .32 - it was too hard an alloy. At .320" it was too hard to load in the .320" land to land barrel. Pure lead .320" round balls from a DC Lee mould, marked .319" was easy - with the .020" patch or the .0235" patch - no different. Small diameter pure lead balls form into the rifling easily.
In my Rice .36, I can load a .350 pure lead ball with .020" patch, without a short starter (choked up rod only, then patch & ball pressed into the bore, then down) - that is how easily small balls form into the rifling, IF they are soft lead.