Perhaps the Falklands war? Argentina circa 1982 was stagnating but still about the 20th largest economy in the world. Taiwan is also sitting at about 20 right now.
Of course, a PRC/ROC war is likely to be much much more serious than the relatively minor conflict that was the Falklands war.
I'd think that Argentina of the junta wasn't quite as important economically as Taiwan is now, but I'd have to research to compare that. I would also imagine Taiwan's HDI is quite higher to Argentina's was back then. Another factor of note is that the junta was going through a shaky transitional period while Taiwan's democracy is fairly stable. Not to mention that while mostly diplomatically unrecognized, democratic Taiwan probably isn't a pariah in the same way a military autocracy like Argentina was.
Of course, a PRC/ROC war is likely to be much much more serious than the relatively minor conflict that was the Falklands war.