Why Victorious could not easily take Sea Cat

Why could HMS Victorious not simply receive Sea Cat during her 1963 refit?

The launcher required magazines, electronics, and support systems that her repeatedly altered hull had little room to accommodate.

HMS Victorious shows how earlier reconstruction choices constrain later carrier upgrades. Sea Cat required a missile magazine, electronics, hydraulics, and other support equipment as well as a visible launcher. Repeated alterations had already consumed much of the old carrier's usable internal margin. A larger, newer design would have offered more volume for later weapons and their services. Building the Malta class would therefore have produced ships with greater modernization potential.