A variety of PE and Resin detail sets have been released by Big Blue Boy this past August. While they cover mostly post WWII vessels for railings, radar, weapon systems and more, it also includes a set for an Italian WWII heavy cruiser.

For the 1/700 sets, they are, with their product number preceding the descriptions:

70022 H.M.S Type 42 Destroyer Batch 1(for Dragon)
70027 USS Detroit AOE-4(for Pit-road)
70092 JMSDF Hayabusa-class missile patrol boat（for Aoshima）
75023 JMSDF Mk 42 5"(127MM)/54 CAL GUN (image not available)
75024 USN Mk 42 5"(127MM)/54 CAL GUN
75025 OTO Melara 76MM/62 Cal SR Gun
75026 HMS Mk8 4.5"(114MM)/55 Cal Gun

For the 1/350 sets:

35050 Railing for Italian Heavy Cruiser POLA (for apparently the Hobby Boss kit)
35503 Mk -141 Harpoon Missile Launcher (can be used iowa class)
35504 Mk -141 Harpoon Missile Launcher

Check your preferred hobby retailer if they have these items in stock.