Co-trainer Brian Anderton confirmed Johnson's engagement shortly before Include's track gallop at Wingatui on Saturday.
The Gallant Guru filly chased home McDonald, an unraced filly out of McMammoth, galloping her last 600m in 38.5 seconds.
Natuzzi also galloped between races on Saturday. The son of Coats Choice galloped with an unraced King's Chapel-Solo Star stablemate, cutting out his last 600m in 35.7sec.
Johnson will carry the hopes of Wingatui twice, as he has accepted the ride on Natuzzi as well.
Trainer Paul Richards said Natuzzi, along with Include, would leave Wingatui tomorrow morning for the trip north.
''That [gallop] will tighten him up nicely,'' Richards said.
''He might do a bit of half or three-quarter work on Tuesday morning, but that will be it.''
Natuzzi is travelling to Trentham to defend his listed Lightning Stakes title won at the corresponding meeting last year.
