Hi Don,
There are two signed rifles shown in the book "Kentucky Rifles & Pistols 1750 - 1850" by KRA and there is an attributed S-L rifle shown in "Early American Flintlocks" by Hartzler & Whisker. Maybe these references are already on your radar?
Interesting builder of seemingly scarce surviving rifles. I would love to see a pic of your remnant parts. Especially if you have a signed barrel, I would love to add his signature to my photo collections of builders signatures. tim