"You'd make an A-1 gravedigger."
"Everyone can be a sucker once in their life."
"A Mexican way to liven up a party."
Did people say these things in the 1800s?
Possibly, but it seems a little contemporary for the period.
shareI assume you're questioning the use of the terms "A-1", "sucker" (meaning dupe), and "livening up a party".
The term A-1 (used to mean "first-rate" or "top quality") goes back at least to Dickens in the early 1800s, and would not have been out of place in common American postbellum speech.
Calling someone who has been deceived a "sucker" goes back at least as far as A-1 (1830s) and was possibly used even earlier. It would have been a well-known term to Hogan and Sara.
"Livening" is probably anachronistic. It's more likely a person at that time would have said "enlivening a party"; the shortened form isn't attested until about twenty years after the period in which the movie is set.