Yes. A republican victory would have been assured simply by France and Great Britain giving the legitimate goverment the same type of support as the Fascist powers gave to Franco; it was never going to happen, but lets assume it does (we could have left leaning goverments in France and GB).
You could then have a Gertman/Italian attack on Spain, with a British defence; so the focus in the Mediterranean would move west, to protect Gibralter. But the odds would be against the British, unless they held some territory and managed a stalemate until operation Torch, not in North Africa, as there would be no conflict there, but a joint US/GB landing in Spain in 1943.
Also, don't forget the Yugoslavian option. Though communist Tito was against the Soviet Union, so the USA armed him as a result; and it wasn't until a raprochment with the USSR that Yugoslavia began to use mostly Soviet equipment. Your main problem would be in keeping Spain together as single political entity, the odds are that the Catalonians and others would break away, again like the fate of Yugoslavia.
The darwings look interesting, but I can't comment on their viability