I’d rather have a 12 mpg 13-second car than a 14 mpg 17-second car.
Just sayin’.
A stock 4-barrel 455 is stone-reliable just the same as a boring 2-barrel 350 is.
Both would look the same when the hood is open, grab a stock 4-barrel air cleaner while you’re doing the 455 swap.
It’s a neat fairly well preserved old basic transportation car but hardly sacred ground, a few nice bolt-in modifications won’t ruin it.