[TigerLikesRooster]

traditional hostility between Park's family and the Communist Party of China going back to World War II

This is a stretch. There has been no long-running hostile relationship between Park's family and Chinese communists. At the time, the elder Park was merely a lieutenant, who was a regimental staff officer . After Japanese Empire was gone, it was not his war anymore. It is not like the relationship between Chinese nationalists and Chinese communists.

for pushing for peaceful unification with the North.

There were some talks between two countries. It was a way to cool down the escalating tension. Neither Korea was interested in giving up its own political system for unification.

[AdmSmith]

China is not among nations invited to attend North Korea’s key national anniversary next month, a diplomatic source said Monday, reflecting strained political ties between the allies.
http://english.yonhapnews.co.kr/news/2015/09/21/0200000000AEN20150921005700315.html