Richard,
I think that is a superb project! I viewed all 3 links you provided and, honestly, the first one was the most informative.
Insofar as the tuning, the first vid explains it very well. The guy goes step through step with disassembly, troubleshooting, takes his time, and comes up with a good solution even though this is the first LeMat he has seen, and then reassembles it to working condition. I give the guy 6 stars out of 5 for his presentation.
I like Mike Belliveau's videos but they do not explain much. The Lodgewood ad shows what they can do to defarb a gun, and that is all.
I collect Pietta 1851 Navy .36 type guns and would very much like to have a Pietta LeMat but the price is way out of my range, sir.
I wish you well with your project and am looking forward to pictures, PICTURES!
Regards,
Jim