I do not believe there existed a time where ROCAF could contest air superiority with PLAAF.
1. In the 1970's and 80's they were using F-104s and F-5s against J-7s and J-8s. F-104s were obsolete, F-5s were similar to J-7s. Except PLAAF had 1000+ J-7s at the time.
2.
, which is contemporary with
.
3. In 2000 PLAAF acquired Su-30 MKK. Taiwan has no response to this... and there was no looking back after this.
All of Taiwan's claimed air to air victories in the 50's and 60's are just that - claims. It doesn't mesh with their known historical performance. It's about as credible as Indian claims.
Taiwan's survival since the 70's has mostly been political and economic, not military. Taiwan lost the entire island of Hainan in 1950 in a crippling amphibious defeat where the PLA got a 1:6 kill ratio in their favor, highly unusual for amphibious operations.