I'd also look at ranges of Italians and Romanians- any with a cap, sidecap, fez or beret would do. The guerillas increased their activity after '43, and captured italian weapon and uniform stocks featured rather heavily. There was also a certain amount of regional variation, for example most photos I've seen of ELAS guerillas in Epirus show them wearing visored caps, either captured italian ones or at least closely modelled on them (heck, you could throw in some Afrika Korps in greatcoats and caps and they wouldn't be far off the mark!). The British also supplied battledress and some weapons, but the ammo pouches typically weren't, or at least they do not seem to feature heavily in photos- maybe some commandos would fit the bill. Also look at Spanish Civil War figures, again for folks in sidecaps and berets.
Unfortunately 28mm is not my scale so I can't point to specific ranges that would be most suitable.
Aris K.