TAI already upgraded PAF F-16A/B Block 15 to near Block 50/52 standard.
Notably They got
AN/APG-66(V)2A Radar with 83 km, upto 150 KM range, not the more modern AN/APG-68(V)9 Radar with 110 km - 150 km plus?
And MLU structural upgrades.
In this, major upgrade include Link-16 Data Link, AN/PYQ-10C) Simple Key Loader (SKL) cryptographic modules to carry/install cryptographic materials,
AIFF, missile handling ground equipment.
$686 is a large sum for Pakistan, but looks a large sum will be consumed in labor, training.
So both older A/B 15 MLU, and new 18 Block 50/52 will be at par operationally.