You’re right on the John Wayne version being an all-around better TRUE GRIT than the remake.
It is a cliche that Glen Campbell can’t act but in reality-land he can act and he was right for the role.
When I was a kid I thought Glen Campbell was awful! But seeing it again - and then seeing the thoroughly miscast what’s-his-name made me realize that he wasn’t really that bad. He is very coached in his line readings (Jeff Corey - were you responsible for that?) but he was physically so right for the part - down to the lettuce for hair! The original is much closer to the book despite what Texans may think, lol.