A lot of the original trilogy SW stuff was just cobbled together from surplus and junk, so using some suitably-modified WW2 figs with a few sci-fi greebles would work well. I'm sure that there are other Rebel uniforms and troop types intended for other operational theatres beyond those seen in the films too (which gives you more freedom).
You could get a couple of the bendy plastic troopers and mould the heads for converting your own too. I know the scales tend to be reasonable for such things as I've seen bendy plastic Clone Troopers bodged onto other models previously.