Any bulk 38 S&W brass or loaded rounds will work fine. The case is identical. The 38 S&W factory loads are still available and still made to day but with 158 grain bullets. You might actually find these loads a lot more pleasant to shoot than the heavy military loadings.
Most pistols chambered in 38/200 are relatively light. The original milspec load is very stout in them. I often load and shoot the 158 grain and even the 125 grain bullets out of my pistols.
Winchester, Hornady and I believe Remington, still load the 38 S&W, maybe others as well and they are a lot cheaper than Fiocchi.