How rebuilding turned the Kongo class into fast battleships

Did reboiling, up-gunning, and up-armoring simply modernize the Kongo class, or did the work change its classification?

The extensive internal rebuilding transformed ships that began as battlecruisers into fast battleships.

The Kongo class began as battlecruisers, but its later reboilings, up-gunning, and additional armor were not cosmetic changes. The reconstruction required extensive internal work. In this functional account, the cumulative result changed the ships' classification, leaving them as fast battleships. An extensive rebuild can alter what a warship is rather than merely extend the life of its original design.