* Size and Weight: The 454 is substantially larger and heavier than the engines that came stock in a '77 Caprice. This necessitates modifications to the engine bay, possibly including firewall modifications, and potentially suspension upgrades to handle the extra weight.
* Exhaust System: A new exhaust system will be needed, as the 454's exhaust manifolds and pipes won't fit the existing setup.
* Transmission: The transmission will likely need to be changed to one capable of handling the 454's torque.
* Mounts: New motor mounts will almost certainly be required.
* Cooling System: The stock cooling system might be inadequate for a 454. Upgrades to the radiator, fan, and possibly water pump might be needed.
* Wiring: The wiring harness will likely need to be modified or replaced to accommodate the 454's electrical needs.
In short, while it's *possible*, it's not a simple bolt-in affair. It's a significant undertaking that requires mechanical skills, fabrication abilities, and possibly professional help. You'll need to research specific modifications needed based on the exact 454 you're using (different years and variations exist).
