, Welcome to the wonderful world of traditional muzzleloading. You have asked a couple of questions that will bring out a lot of controversial answers, especially since you want a historically accurate fowling gun.
Before I answer them, I am going to suggest that you get a copy of Grinslade's book, "Flintlock Fowlers". He covers the fowling guns that were being built from the earliest gun through Revolutionary War.
First, we need to know what part of the country are you trying to represent with your historically accurate fowling gun? Gun stock architecture changes from New England through the Carolinas. Do you want a gun built in the colonies or more commonly in England with a few Belgian and French examples also known.
The barrel will likely be long. The length of 44 to 46 inches and longer seem to be common.
TVM makes a solid, functional, reliable, and affordable fowler that is built in the essence of the era, but not a true representation of a historical fowling gun of the era.