As
@Gripen9 noted, it was in addition to the F-16s. In fact, these tests were happening while the F-16s were being delivered to the PAF.
In the early 1980s, the F-16 was still a fairly pricy platform, at least for the PAF, which also needed to replace the F-6s. So, they had a parallel project for a lightweight multirole fighter, and evaluated the F-20.
When that fall through, the PAF worked with CAC and Grumman to modify the F-7 into the Sabre II by giving it the AN/APG-66 radar and GE F404. This got too costly, and Sino-US issues basically killed it.
Then, according to AC Kaiser Tufail, Dassault came and offered the Mirage F-1 with complete ToT plus a huge stockpile of ATAR turbojets. However, the PAF was interested in this interesting test unit where they paired the F-1 with the M53, but as it was a demonstrator, Dassault couldn't offer it.
Finally, by the late 1980s, the prices of the F-16 started to really drop thanks to scale. The general trend of the major F-16 users was to just build a 120-150+ fleet, e.g., Turkey, Egypt, Taiwan, South Korea, etc, and it was no different for where the PAF should technically head to.
By that point, the PAF opted to basically replace the F-6s with F-16s in batches. ACM Qureishi said in an interview in the 1990s that had Peace Gate III/IV completed, the PAF would've started talks for another 50-60 F-16s. So, we're talking like 150-160 F-16s in total.