I decided to turn the sprue of Krauts that came with Wargames Illustrated into a set of International Brigaders.
They came out better than I expected! Threw some green stuff and Empress heads on them and I was all set.
I filed down the pointy nazi officer's cap so it resembled a Spanish one.
Next up I'll try the Warlord Russian winter sprue, which I expect will work well too, given the Republicans used soviet equipment.