The closest Kohler to the Ultramax would be the Cimarron one-piece.
I removed one of those for a client last week, and installed the TOTO Soiree.
The Kohler wound up in the dump. If your friend lives near me, maybe I can start giving him the used Kohler's I'm pulling out. It could save us both money.
Other Kohlers that get removed are the Santa Rosa models.