Welcome to the Forum.
I think that the L&R replacement locks are for the rifles and are a bit too big for use on the pistols.
As was mentioned, the number of flintlock pistols is pretty limited.
You might check around for a used one.
Generally speaking, the ones made in Italy are pretty good but some of the older ones made in Spain have soft frizzens and don't spark well.
As a side note, CVA used to be the big traditional muzzleloader importers and they bought all of their sidelock guns from Ardesa, a company in Spain.
That is the same company that Traditions currently buys their sidelock guns (pistols and rifles) from.
From what I've read, the newer Ardesa imports have better locks on them but, IMO the Italian guns are better.
If a smoothbore .50 will work, Pedersoli makes a Queen Anne style pistol and you may be able to find a used one. If you do, be sure to let us know because unmodified it doesn't have very positive ignition.
I found the problem and came up with a solution if your handy with a drill and a tap. I can link you to my fix for it here on the Forum.