If you really want to learn how to fit parts together and understand that little dance that goes on between several parts at once, buy a Traditions Kentucky pistol kit and learn how. For 230 bucks you can figure out how to rob Peter to pay Paul and determine exactly how much you need to steal to get the job done.
When folks say Traditions kits are junk, they're half right. Out of the box they're complete garbage. Poor inletting. Poor metal to wood fitment. Etc. But all of the parts are solid and 100% serviceable.
You just have to be ready to break out the chisels and files and remove some wood and metal.
Had to push the tang inlet down more than .100 inches so the barrel would make contact with the barrel channel. This in turn dropped the drum more than .100 inches.
Now the fun begins.
Removing material from the lock plate/bolster is a nonstarter. It would chew into the area of the bolster that houses the top of the mainspring.
Just have to grab the files and remove material from the bottom of the drum. Just enough so the tang, barrel and drum make contact at the same time. In this case, had to remove a tad more than .100 inches from the drum.
The only drawback to this kind of set-up, is you must remove the barrel in order to remove the lock. But it's worth it to have all the parts fitting together well.