Why heavy-cruiser hulls make better carrier conversions

Which cruiser types are best suited for conversion into aircraft carriers?

Heavy-cruiser-sized hulls because their structure and dimensions better support carrier top weight and internal arrangements.

Carrier conversion adds substantial top weight through the flight deck, hangar, lifts, and island. The hull also needs enough length and beam to provide a useful flying deck and aviation spaces. A design intended to carry heavy-cruiser armor usually offers greater structural strength than a typical light cruiser. Its rigidity and internal subdivision make the conversion more practical and reduce the amount of fundamental rebuilding required.