There was a time nobody surpassed James Clark Sr for Colt 1911 Government smithing. (Or his winning of national shooting championships !)
His son James jr, from all reports carried on admirably in the old man's steps. The old man, now dead quite a few years, has recently been joined in passing by son James.
It probably would be advised to get some current updates on the companies work. While they once were considered very proficient on Smith & Wesson revolver work also; I read some comments, (not confirmed), they have withdrawn from the S & W work ???
When Jim Sr. ran the place, they were unsurpassed. Towards the end of Jim Jr., they started having issues. I'd want to see the work they are producing now, before I'd rely on a reputation from long ago.
I bought a Clark Custom barrel for my S&W Model 41, perhaps a year ago. It was a drop in part, no fitting needed. The Clark Custom barrel, along with an Aim Point Pro red dot device shrunk my groups quite substantially.
Based upon my experience with the Clark Custom barrel, I conclude that Clark Custom has some quite talented employees working for them.