Another use would be as Bulgarians, who, despite their joining the Central Powers in WWI, modelled their uniform after the Russians.

A better choice for Mexicans would be early great war British.

On a vaguely-related note, I use the HaT reissue of the Airfix WWI British as Japanese for 1905. They are 1/76th scale and so appropriately smaller than the 1/72nd scale HaT Russians, just as the average Japanese soldier was noticeably smaller than his Russian counterpart in 1905.

I chose to paint these converted Japanese in 1905 khaki rather than 1904 blue so that they could stand in for Mexican Federales. My long standing plan is to use Airfix/HaT WWI Americans as Pershing's forces for the 1916 intervention. I'm at a loss for a reliable source for Villa's forces. IMEX promised me they'd be released in September of 1999. I remain optimistic that they will be made some day by someone. Murphy dictates that when they do come they will be massively overscale.

Boxer rebellion Russians - without peak.

WW2 Soviets - after headswap.

About the Mexicans, if metal is an option you might want to check Shellhole Scenics and Early War Miniatures who do a whole range:
http://shellholescenics.co.uk/index.php?main_page=index&cPath=254&zenid=a6hl8jcispk55afp9p89eddno0
http://earlywarminiatures.com/product-category/ww1-1914-1918/ww1-1914-1918-mexican-revolutionary-period/

No connection to the companies. Regards, Pat

1.russo-japanee war
2.russo-turkish war 1877-78 ( imperial guard had peaked caps)
3.boxer rebelion
4.russian colonial wars of 1859-99 (caucasian wars)
5.russian civil war
6.chinese civil war