You might reconsider dropping the front end to remove the engine. I just finished pulling the engine from our 74 Argosy out the front. Other than removing the radiator and the front grille there wasn't much else that had to be done. True the engine was a 350 but the 350 and the 454 are not much different in height. With the 350 there was lots of clearance. More than enough for a 454 which is what was in the Argosy when it was new. Our Arosgy had a rebuilt 350 in it only because some previous owner had pulled the 454 (from the front) to put in it a race car
I will be reinstalling a fresh 454 in the Argosy and it will be going in the front.
I bought one of those intake manifold lifting plates that bolts to the intake manifold in place of the carb. At first I was concerned about the strengh of the aluminum intake manifold. I was concerned that the mounting studs threads would strip. I did some research and found a sight that did some testing of these lifting plates and found that even when lifting an engine with an aluminum intake the plate welds broke before the holes stripped. The testing pressure was 10,000 lbs which is 10 times what a 454 weights.
I found pulling out the front was actually a lot easier than I envisioned. A standard engine hoist is what I used. I set it up so the plate was bolted to the chain right under the lifting are to provide as much clearance as possible.
Bottom line is since you still have to remove all of the stuff from the front like the radiator, etc I'd give serious consideration to pulling from the front instead of dropping from below.