Good to hear, they are wonderful rifles. Cromwell is going to be your best source but there is also good information in George D. Moller's
American Military Shoulder Arms, Volume II: From the 1790s to the End of the Flintlock Period.
Will you be using brass or iron furniture? The First Model Rifle had round sheet metal pipes (no facets) with rings front and back.
You can do a search at the Virginia Museum of History & Culture's website -
https://www.virginiahistory.org/, they have an excellent collection of rifles, muskets, pistols, bayonets, swords and other items from and having to do with the Virginia Manufactory of Arms. If you live within a couple hours drive of Richmond, Va., it may be worthwhile to take a trip to see some of the items.