It has been my observation that the 53 is a bit small to visually handle much of a hard top. Some of the executed versions I have seen are just terrible looking. Nothing ruins the look of a classic motor yacht any worse than an aftermarket abomination. That said, I think if done carefully it can look good.
The very best after market Hatteras hard top I have ever seen is aboard a 1987 Hatteras 63 Motoryacht called "Gran Slan" that is currently for sale on YachtWorld. There are some very good photos of that top in the specs where you can see how it integrates with the arch, etc. It is beautiful in person and does not interfere with the lines of the boat at all. Now, it is also NOT enclosed, which makes a difference. This is also a 63' not a 53' boat.
What you wish to do can be accomplished nicely. My suggestion would be to plan carefully and proceed slowly.