Lots of answers to give.
First, some general remarks regarding my mod.
I have the following period/lines
WWI (1914) =
- Infantry, Marine, Cavalry
Inter war = very end of WWI uniform, or very early WWII
- Infantry, Marine
WWII = 1941-1944
- Infantry, Marine, Paratrooper, Commando, Resistance
1945-1960
- Infantry, Marine, Paratrooper, Commando
1960-1975
- Infantry, Marine, Paratrooper, Special Forces, Guerilla
1975-1990
- Infantry, Marine, Paratrooper, Special Forces, Guerilla
1990+
- Infantry, Marine, Paratrooper, Special Forces, Guerilla
It could be possible to add MG or Assault Engineer with flamethrower, or AT gun, for a few civ.
Currently, I'm using late WWII unit for the 1945-1960 slot.
So I'll use the British infantry with sten for that.
For the moment, I have many placeholders, with some variation of your Mauser or Garand Pack, that would probably be replaced with some different weapons should you make them.
On this page, I try to keep track of what is available and what could be done.
http://stephane.f.david.free.fr/CivMod/All_LandModernUnits.htm
So, what could you do with a Sten?
Not many reference...
British marines, 1950
But you could also make "what if" Indian, Egyptian or Arabian marines or paratroopers. These countries where under British rules. That could be useful for epic mod that want to cover this time period for these civs.