Help with a Exmark laser z hp 48 inch (motor/hydro question)

Just picked up a used Exmark laser hp 48 inch model #LHP4820kc (serial number 514029) for $1500. It has 1250 hours on it and was used commercially. I will be using it on my own property and probably 50 to 75 hours a year. I was thinking about rebuilding the engine and hydro pumps this winter so it would be ready next year. It runs fine and drives fine but would rather rebuild now before problems later.

The question.
The engine doesn't have any badging but I believe it is a Kohler...

Help with a Exmark laser z hp 48 inch (motor/hydro question)