Phil,
The CVR(T) Life Extension Program wasn't just a case of pulling one engine and fitting another. The clutch and gearbox need significant modifications to support the extra torque, the hull had to be modified to provide the extra air intake slot, deck plate and louvres were all replaced or modified, along with both bulkheads. The accelerator linkage is replaced with a cable, engine mounts in different places, etc etc.
My main concern would be killing the gearbox by bolting another engine to it without upgrading it.
Chris