While the AU is pretty well thought out and your drawings are high quality, I just don't see how putting that many miles and modification on World War 2 hulls is feasible. The tartar plus FRAM update just seems like too much weight to put on a Gearing hull and considering those are already twenty years old by the time of the modernization, can't be completely cost effective. Maybe having a group of tartat only, and a group of FRAM only upgrades would be better but both seems like a bit of a stretch for these hulls. I would get rid the Shikaoi class DDG absolutely if anything though as by then the hulls are completely warn out and I really don't see a Mk.41 being feasible on a World War Two destroyer hull. Thats a massive upgrade for a worn out hull with at most, ten years of service left, which is really optimistic. The only RL comparison is Taiwan and while they did retire their upgraded Gearings around the same time, as you are, I would not consider that a sign that doing so is a good strategy, as IIRC it was encouraged by desperation.
http://www.shipbucket.com/images.php?di ... %20III.png Here is an example that the great Darth Panda drew, of their upgrade.