You are correct. Busch bought the cabin after it had been used at the St. Louis World's Fair by a coffee company. (They had moved it from Webster Groves where it had been moved by some real estate developers.) Busch had it erected on his estate property facing Gravois Road just west of the creek that Grant Road runs along. The whole thing became Gran't Farm. White Haven, the plantation house of Grant's in-laws, is east of Grant road and south of the Clydsdale pasture. BTW, as if all of this wasn't BTW, Grant met his wife because he was invited to the plantation by his West point roommate, Frederick Dent. Dent, who had remained in the Army, became Grant's Aide-de-camp in the Civil War after grant rejoined the Army.
You're up @InspectorJon.
There's Mount Vernon, Monticello, and 'Hardscrabble'.