I think a Russian AC-130 is not what they need.
They might find something else is better and more useful, but I don't think putting large calibre guns in transport aircraft makes them cheap fire power platforms.
The aircraft is already in flight so gliding bombs probably makes more sense in terms of weight capacity and effect on target.
What I think they should implement is a storage/release rack for transport aircraft that can be extended out the rear of a transport aircraft in flight to release dumb bombs of various sizes and weights that together with a Gefest & T system achieve the necessary accuracy to make them even more effective than any gun system they could mount.
Very simply a release mechanism that can drop 1, 2, 5, 10, 20, and 50kg bombs continuously or individually on targets, but could equally carry 100, 200, 500, 1,000, 1,500, 3,000, 5,000, and 9,000 kg HE bombs too makes their entire transport fleet effective bombers against a poorly equipped enemy that could drop more ordinance on a target than any AC-130 could fire in the same time frame.
The problem with the AC-130 is that to use 30mm cannon effectively you need to be within about 3km of the target and that includes altitude as well as horizontal distance.
With a bombing rack that could be installed into the rear of any transport aircraft of suitable size... you could make a set of systems... one being a bomb rack to handle and release out the rear of the aircraft bombs, you could also create another mount for carrying water for fire fighting duties, and another for fuel for inflight refuelling duties.
The Il-272 would actually be better suited to 10km altitude bombing than the An-12 which would be operating at lower altitudes and much slower... the point is that the extra altitude means more kinetic energy for the bombs... you could probably use small guided bombs of 10 and 20 kgs weight that are pointy and do not have HE inside them... their impact speed being enough to penetrate most vehicles from above.
The best thing is that any aircraft could be used, you don't need special aircraft for the job... make the Gefest & T system modular and pod mounted with optics and sensors in an external wing pod or two that could be hung under wing pylons of any current or future transport plane.
When you need support load it up and mount the pylons and off you go and when you are finished take them off and return to transport duties.