Considering the number of Mirages and F-7s that need to be replaced and that the PAF may max out on JF-17 at 200-250. It will still need at least another 100 aircraft to maintain its current fighter numbers. Buying a large number of used F-16 air frames (with PAF funds) and putting them though a MLU in the US (under CSF funding) are probably the best way to get the most bang for its buck. Coupling this with large acquisitions of munitions such as Aim-120C7, Aim-9X, JSOW and JMHCS helmets.
If the PAF can get approved to buy the Block 70 it can then try get all those used F-16s upgraded with AESA radars.
Also, now that sub-systems/accessories are being sold, PAF should look at getting upgrades for its current F-16s like a towed decoy, DRFM based Jammer pods, JHMCS for all F-16s, Inflight refueling probe enabled conformal fuel tanks for the C/D models, upgrades to the ESM or MAWS to better detect missiles fired upon the F-16, and datalink upgrades to better share the information from the sniper pod with the rest of the Air Force and the Commanders on the ground.
down the line, if Pakistan is allowed to buy more F-16s, new or used, or even if Pakistan is allowed to just buy more weapons, it should serious try to buy the sensor fuzed weapon in large numbers along with cruise missiles like JSOW to deploy them to counter the COLD START Integrated Battle Group Threat. This will go a long way in deterring Indian aggression, when it knows it’s forces will be decimated. sensor fuzed weapon strikes on a platform like the JSOW can also be a great way to deal with pop-up threats like the S-400. The many skeets can engage and re-engage the many elements of an S-400 or other air defense battery.