You Have a P-58 Naval Rifle
The P-58 Naval Riflse were made for the British Navy by a variety of different contractors.
You will be happy to know that your "Naval Rifle," (as it was called) was one of the most accurate of all the muzzleloading Enfields because it employed 5 land and groove rifling with a 1 in 48 twist. Their accuracy is legendary.
By the way, your Naval Rifle has the "3rd Model" barrel bands, also known as the "Palmer Bands." These were found on most of the Enfields imported into America during "The War of Northern Aggression" by both the Union and the Confederacy.
During the latter part of the war, General Robert E. Lee approved the organization of special Sharpshooter units. These units were made up of the best marksmen and they were issued Naval Rifles (or the army version of the same) along with British made ammunition. These Sharpshooters performed picket duties and also acted as snipers. They were an elite unit.
Now, only two factories in England manufactured "machine made," fully interchangeable" Enfields. This was the government armory at Enfield Lock and also a private company: The London Armory Company. Their lockplates were marked "LACo."
Interestingly enough, even the parts between arms manufactured by Enfield and LACo were fully interchangeable with each other! Most of the machinery used in those two armories was made in the United States and set up by armory workers from the United States.
As for the arms marked "Tower" on the lockplates:
These were made by a much older system for manufacturing firearms. They were made in a "Cottage Industry" system.
This was a highly specialized system. For example: Locks were made by "lock makers" and these artisans had a contract with the British Ordnance Department. They would deliver their completed locks to the Tower of London and be paid. (If, of course, the parts passed inspection.) The same is true with the barrel makers, furniture makers, etc.
Then another set of contractors, "Stockers" would stop by the Tower and be issued all the parts for a specific number of arms. They would stock the arms and return them to the Tower and be paid for their work. Of course, arms made under this system were marked "Tower" on the lockplate and were government property.
Now, during "The Late Unpleasantness Between the States" there was such a demand for Enfields from both the Union and Confederacy some gunmakers would mark their lockplates with the spurious "Tower" marking simply as a sales tool.
Also, you will note all over your Naval Rifle you will find a series of small, stamped letters and other markings. For example-if your ramrod channel is not too worn you will see some letters stamped INSIDE THE RAMROD CHANNEL. This will be the mark of the contractor that stocked the arm.
You will also find other letters stamped inside the lockplate. This will be the mark of the lockmaker. Same with the underside of the barrel, etc.
After you have decipered all of those markings, then go to:
www.mlabg.com/
This is the website of the Muzzleloading Association of Great Britain. Go to their "Forum" and then to their "Rifle & Musket" web page. Then just list the markings you have found on your Enfield and I am sure someone can tell you the name of all of those individuals and/or contractors that made parts for your arm.
Keep in mind you have a "Non-interchangeable" Enfield; so if you have to replace any parts, you will most likely have to do a bit of hand fitting.
You can order a 90% Enfield stock from S&S Firearms made by Dunlap. So replacing that stock should not be much of a problem. GOOD LUCK!