Your idea is a bit too difficult to implement! Perhaps you could begin by establishing a joint military coordination center—specifically at the level of military operations, rather than at the level of politics or diplomacy.
BTW.
China does indeed permit the export of the Y-20 series of transport aircraft. However, the People's Liberation Army Air Force (PLAAF) currently faces a significant shortfall in the number of these aircraft; although the Xi'an Aircraft Industrial Corporation (XAC) is making strenuous efforts to accelerate production, a substantial gap remains. Consequently, even if the Pakistan Air Force (PAF) were to place an order immediately, there would be a very long wait due to the production schedule.
The Il-78 tanker-transport aircraft currently operated by the PAF features a multi-role design, allowing it to also function as a transport aircraft.
Naturally, this depends on the specific cargo you intend to transport. In general, the Il-76/78 series and the Y-20 series belong to the same class of transport aircraft, though there are some differences in the details.