You are not permitted to download, save or email this image. Visit image gallery to purchase the image.
Stead took over last year as coach from Mike Hesson, who surprisingly quit less than 12 months out from the May 30-July 14 World Cup.
The 46-year-old has selected a mostly-settled squad for the three-match series starting at Mt Maunganui, with three or four players vying to force their way into World Cup contention.
With Colin de Grandhomme rested and Mitchell Santner still working his way back from knee surgery, all-rounders Jimmy Neesham and Doug Bracewell have both been recalled after more than a year out of the side. Attack-minded wicketkeeper Tim Seifert will also make his one-day debut.
"It's really now looking ahead to the World Cup, being clear on the game plans we want to use and making sure the roles we want to get people in that we're playing to those roles as well," Stead said.
"We're still looking at some places within our team. We want to see more of the all-rounders, we're looking at Tim Seifert as a back-up keeping option as well.
"It's definitely a trial period still."
While the focus might be on the players, Stead added that against Sri Lanka they would also test their tactics and game plans for the global tournament.
England, the world's top-ranked ODI side, credit New Zealand for the way they revolutionised ODI batting under the captaincy of Brendon McCullum at the 2015 World Cup.
Eoin Morgan's side have built on that, regularly scoring in excess of 300 in home matches. In the 42 ODIs played in England since the last World Cup, the hosts have posted 20 totals in excess of 300, with three more than 400.
"They're (the Sri Lanka matches) about tweaking, looking at the style of play and how we want to play and looking at the options who fit those roles as well," Stead added.
"The biggest thing for me is looking at the style of play, game plan, and looking ahead to the World Cup, where we know it's likely to be 300-plus scores.
"I want to make sure we get our heads around that as well."
The first two games will be played at Mt Maunganui before the sides move to Nelson for the final match on January 8. Sri Lanka's tour ends with a Twenty20 game in Auckland on January 11.