Your correct in that the periods look different for the uniforms of the 20' & 30's. They actually look more like the Nazi SS uniforms listed for Michael4.

https://www.renderosity.com/marketplace/products/103545/german-ss-black-uniform-wwii

Would that work with conversion on a G8 character? I don't have any M4 items to test with.

I have the Inspectors Uniform but thought that too plain, but had pretty good results using the https://www.daz3d.com/h-c-police-uniform-for-genesis-3-male-s uniform converted to G8, and with Big George as well after pruning hidden geometry. The badge & metal items are textures though rather than geometry. Went looking for a Badges collection and nada, only a tutorial on making them.