and a quick neverbuild.......
some sources note a late 1950's proposal to replace the aft 120mm turret with an guided missile launcher. while it is not mentioned which missile and launcher it is exactly, the only likely candidate is Tartar. as the Mk 13 was first exported in 1965, I would see this as the most likely fit (as the Mk 11 was never exported)
weight wise and space wise the system fits, although a little ballasting in the gun magazine might be required to recover the stability lost from the heavier director. to my surprise, this conversion would actually be possible, although I have to note that there is just not enough weight and stability reserve to fit an 3D search radar in my opinion.