I'm interested in the voteshare for the KMT from the 1960 election to the 1990 election. All were indirect elections I believe but I have been unable to find data on what % the winning candidate got.
You're looking for a document called 歷次立法委員選舉投票率統計（民國58年－93年）, which is the National Assembly results from 1958-1993. Unfortunately I cannot seem to find this online anymore, you may have to go to the National Archives and reach out to someone there for help.