The components of the 455 and 428 will be more important than which motor you choose. Look at the heads--which heads, large valves heads for the 455, valve guide wear, number of valve jobs, compression. Which intake and carb do they have? Have the motors been bored previously? If so, is one of them already at 60 over?--which may be the limit. You can make either of them do what you wish. Look for cracks in the block and surface of the heads.