<The government of the south was regarded, correctly, as a puppet regime financed by Western powers, whereas the north was home-grown and nationalist.

Get real. North Viet Nam was a Soviet puppet. If the Soviet Union hadn't fallen, there would be a totally different colonial situation in SE Asia today, especially since to no one's surprise, a number of other nations did fall to the Communists like dominos. As it is, the communist governments (except N. Korea) seem to be slowly withering on the vine and allowing more freedom as time goes by.

You are correct in that the governments of South Viet Nam were anything but sterling examples of integrity and honesty.