The true value in front of mernards on 135 seems nice ive gotten parts from there. A friend of mine runs one on the east side CJ small engines his name is Carl hes reasonable.
Took a mower to him 2 years ago. He said it was junk. I told my dad I wanted to take a look at it since I bought it for him a few years earlier. We went and picked it up, brought it home, ripped it apart and found a blown head gasket. 7 dollars in parts and 7 in shipping and it runs like new.
What I am trying to say is I won't take any engine to him.
Watermans at Southeastern and Five Points Rd out by I74 and 465 on the SE side is my go to place for that kind of thing.
Edit: I have never taken riding mowers there, just other small engine stuff. I would guess they do riders too.