The first 215 (paperback) pages all from Jack Delaney’s POV.  I know he did one western in first person, but are there any others where he sticks with one character for so long, that many consecutive pages?

You could be right.
Although, I’m not absolutely qualified to say, because I haven’t read every one of the early westerns, just some. But, even with that considered, I think you still may be correct.