What Britain converts if the Courageous class stays armed

What would the Royal Navy use for carriers if larger Courageous-class ships remained gunships?

It would build carriers from scratch or turn to older battlecruisers and incomplete Admiral-class hulls, with G3-related conversions another possibility.

The Royal Navy still needs carrier tonnage even if Courageous, Glorious, and Furious are too useful to convert. Purpose-built construction is the cleanest answer, but treaty timing and cost may make another conversion attractive. Older battlecruisers such as New Zealand, incomplete Admiral-class hulls, or even G3-related material become possible candidates. The Admiral hulls are especially interesting because work had advanced far enough that disposal decisions existed without every physical step having been completed.