Hey 50calty, I've never done it. But I looked into it in some detail because I have five TC precussion guns and would dearly love to convert one of them to flint (a .58 Hawken).

As Sabotloader said, you can change the lock to a TC flint lock and replace the percussion barrel with a TC flint barrel or Green Mountain replacement barrel and everything will fit fine. But all in all, it just does not seem cost effective.

First, there's the lock. A new lock from TC is $120, although you may get lucky and find a used one on an auction cheaper. I'm not sure what lock you are looking at on the Numrich site, but I doubt that any non-TC lock would be a drop-in fit like the TC would. A cheap lock may very well have problems of its own and trying to modify another lock to fit the TC configuration may bring you to grief.

Then there's the barrel. A new one it going to run in the $200+ range. Or you could have the percussion breechplug on a caplock barrel replaced with a flint breech plug. A flint breechplug for a TC is $28 at Track of Wolf if you want to attempt the modification yourself. Having the work done is likely to cost $50 or so plus shipping to and from whoever you find to do it.