Well, Pedersoli is the only company that offers a "kit" unless you put together a parts kit from the Rifle Shopp or Track of The Wolf, and that requires you complete the lock from cast parts... not for a beginner.
As for books there are several, but don't use them to compare to your Pedersoli... a good shooting gun, but apparently the original that they copied back in the 1960's was a mish-mash of parts. Not a function or appearance problem..., just a historic cosmetic problem for those worried about such situations.
Here are three:
The Brown Bess by Eric Goldstein
Red Coat and Brown Bess by Anthony Darling
A Soldier-Like Way: The Material Culture of the British Infantry 1751-1768 by R.R. Gale.
LD