Barritt forms an interesting centre partnership with Mathew Tait while Dowson fits into a combative back-row featuring openside Steffon Armitage and captain Chris Robsaw.
England Test starters Chris Ashton and Danny Care are also included in the XV while scrum-half Ben Youngs - star of the show against the Wallabies in the second Test - and full-back Ben Foden both provide attacking options from the bench.
The Maori have already given a much-changed Ireland team a bloody nose and Johnson wants to see what Barritt and Dowson are made of at international level.
"This was a great chance to get them in," he said. "When you are picking a squad there are always some players who are unlucky to miss out who could have come easily. This is an opportunity for those guys to play.
"You are always disappointed to get injuries but this has worked out for us in some regards in that we get to look at them at the highest level.
"When we got Brad we thought, 'Let's not bring him all this way to sit on the bench'. It was the same for Phil. We wanted to give him a start.
"They are good guys and were unlucky to miss out, frankly. They are bright enough to know they get a good chance tomorrow."
England: Delon Armitage (London Irish); David Strettle (Harlequins), Mathew Tait (Sale), Brad Barritt (Saracens), Chris Ashton (Northampton); Charlie Hodgson (Sale), Danny Care (Harlequins); David Flatman (Bath), George Chuter (Leicester), Paul Doran-Jones (Gloucester), David Attwood (Gloucester), Geoff Parling (Leicester), Chris Robshaw (Harlequins, captain), Steffon Armitage (London Irish), Phil Dowson (Northampton)
Replacements: Rob Webber (Wasps), Dan Cole (Leicester), Dan Ward-Smith (Wasps), James Haskell (Stade Francais), Ben Youngs (Leicester), Shane Geragthy (Northampton), Ben Foden (Northampton)