Who works on the Lightning/Stallion/P Jr?

[SimmerinLightning]

Can it reasonably be assumed that most SA smiths work on these, or would I need to seek out someone specific?

I don't need anything done at the moment; just a random thought crossing my mind. Maybe someday I might have them slicked up a bit.

[Coffinmaker]

There are some size and small parts differences from the "big guns" but other than that, they're basic Single Actions.  Any "SA" smith
should be able to work on them without complication.
You mention they are working fine for the moment, and, not having any knowledge of your guns, you may find simply changing out the original equipment truck spring will make an amazing difference.  Because the guns are a mite anemic (small) a certain amount of fitting may be required for the springs.  My personal recommendations for springs are "Lee's Gunsmithing Gunfighter" or VTI Gun Parts after-market main springs.  Some internal rubbin 'n' buffin is always helpful.

Coffinmaker