Like I said, I could only see this as purely academic or for some nation like China or Turkey who 1.) had no real organic shipbuilding programs and 2.) would be given ships to help 'distract' the Japanese or Germans.
The old US-destroyers where good at hunting submarines. And as fast troop transports. Or other special jobs. But no aa-role, no upgunning, no complex refit will work. I tried to do something with a 4-funnel myself and decided to drop it. Nothing will work unless you forget about simple physics. Sorry bout that.
Now, the physics do match up- at least in weight and 'swing room' for the weapons.
Whether or not someone would go through the time or effort to refit them might be up for debate... but the Nationalist and Communist Chinese were VERY hard up for ships that even fit into the 'serviceable' category... much less the 'modern' one.
An AA refit isn't THAT complex compared to some- mine is almost a pound-for-pound gun swap. There would be no major below-decks work needed, no changes to the internals. The only real structural work is slightly lengthening the aft deckhouse, adding the podium for the centerline 40mm single, and lengthening the walkway from the fore deckhouse a bit for a director.
Everything else that's changed is subtraction rather than addition... and not nearly as hard.
In fact, my refit probably involves no more work than making them into a fast transport.
And, honestly, how can you say that these ships were 'good at hunting submarines?'
1.) Their armament was all wrong.
2.) Their machinery was all wrong.
3.) Their hull form was all wrong.
4.) Their topside layout was poor.
The only things they had going for them, in fact, as 'good sub hunters' was the fact that they could float and had sufficient speed to chase a fleeing sub. They were hulls in the water at the right place and right time. Beyond that, they pretty much sucked in comparison to the capabilities of ships that were intended to hunt subs.