Tumbling Dice do 20mm (metal) Guards in overcoats. Their heads come separately, so I imagine they are also selling the same castings with other headgear. I already have some of these, so my preference for Strelets is the Alma over Inkerman.

After all, my Airfix guardsmen can only fight so many battles before someone notices that they are wearing uniforms from the 1950s, not the 1850s!