This is not my specialty area, so anyone more competent than me is welcome to comment. But my general idea is no, not really, or at least relative to most Asian dictators of the era. (For examples of what I'm using in comparison, check out, say, Ferdinand Marcos or Suharto. Admittedly not a high bar to cross.) I'd be very surprised if he never enriched himself at all, of course, corruption is still found in South Korean politics today-but at the very minimum, he never let corruption interfere with economic growth or state stability, which is more than you can say for most dictators. South Korea was poorer than Ghana when he took power: if Park was your typical kleptocrat, it would have never gotten anywhere, not least because Kim Il-Sung would have started looking better by comparison.

What I do know is that Park Chung Hee very much represented the younger generation of officers in the ROKA, which took more inspiration from Japanese-style technocratic, pseudo-authoritarian rule than from old style Confucian norms mixed with American democracy, as were the older generals. In fact, one of Park Chung Hee's major initiatives upon coming to power was actually cleaning up corruption among top South Korean businessmen, generals, etc, from what I recall.

Also, one thing that might have helped was Korea's Sino-centric culture. The legacy of the Imperial Exams and the like in countries in the Sino-influenced sphere (Japan, Taiwan, Korea, Vietnam, Singapore) mean that traditionally the process of picking local officials is more meritocratic than in much of colonial South or Southeast Asia, and that the limits of how much local officials can abuse their power on their own are more stringent. Another way of seeing this is comparing the Vietnamese-both North and South-to the Cambodians during the Indochinese Wars, particularly the difference between the VWP and the KR. This isn't just about culture, other things matter too, but IMO, it's an important ingredient.