Why a different empire would need different naval equipment

Would historical naval equipment still suit a non-declining British Empire?

Generally not unchanged; different needs would produce meaningfully different equipment, even where some designs looked similar.

Equipment from the historical timeline would generally not transfer unchanged into a non-declining British Empire scenario. The actual ships were designed around the strategic and institutional needs that existed, while the counterfactual polity would ask different things of its fleet. Some resulting designs might still look familiar because navies can reach similar technical solutions. Important details would nevertheless differ, making force structure a consequence of the altered scenario rather than a catalogue of historical classes.