Otago Boys' High School and Auckland's King's College will join NBHS as the three New Zealand teams at the 20-team festival in the Stellenbosch wine region of Western Cape Province.
The festival is being organised by 2012-15 Springboks coach Heyneke Meyer, who has commitments from 10 top South African schools to play 1st XVs from around the world.
Ratcliffe, who coached the Magpies in 2005 and '06, said Meyer recently expressed concerns about the volume of games school-age players were playing.
"He wanted this festival to be a quality world competition with each team playing two games within seven days. His philosophy is similar to ours and he wants camaraderie and values to be a big part of the week."
Ratcliffe's troops will play Boland High School on March 31 and Monument High School on April 6. Monument High School is ranked among the top three teams in South Africa.
"We're expecting our opposing teams to be big and bulky. Our forwards will be challenged more than ever before. I learnt during my involvement with the New Zealand under-21 and under-19 teams the South African boys play with a bit more physicality," Ratcliffe said.
"If you want to compete with them you need to have more intensity and better technique. If you don't you will get in a lot of trouble."
Key forwards in the NBHS tour party include hooker/prop Patrick Teddy, hooker/flanker Tyrone Thompson, locks Josh Gimblett and Frank Lochore, who is a grandson of All Black legend Sir Brian Lochore, and loosies Sam Henderson and Luke Russell.
Kingpins in the backline include second five-eighth Leo Thompson, first five-eighth/fullback Harry Williams and halfback Angus Kilmister.
The 26 players for the trip, which will cost more than $100,000, were selected from a training squad of 50 which has been putting in the hard yards since November last year.
"We're hoping this will become an annual trip. The motivation for making the South African trip means the boys will train harder than ever before over the summer months," Ratcliffe said.
"The advantage of an April tour is the fact it won't impact on the NCEA exams at the end of the year like a lot of end-of-season trips do."
The tour party will leave on March 29. Ratcliffe pointed out the players will learn a lot about the privilege of their lives and things which are taken for granted in New Zealand.
They will also visit Robbin Island where Mandela was incarcerated for 20 years and they will visit a township school to do some coaching with youngsters.
The full NBHS squad is: Angus Kilmister, Caleb Turner, Connor Wadley, Fergus MacKinnon, Frank Lochore, Harry Devine, Hayden Davis, Henry Williams, Jack Sheridan, Jayden Stok, Jayden Walker, Josh Gimblett, Keegan Christian Goss, Leo Thompson, Tyrone Thompson, Luke Russell, Manaaki Aranui, Max Anderson, Oskar Lynch, Patrick Teddy, Pereiha Hubbard, Qunta Tawhai, Rob Slabberkorn, Sam Henderson, Tiaki Fabish, Treyah Kingi Taukamo.
■ In the wake of the training sessions the 50-strong wider training group have been putting in since November expect the NBHS 2nd XV which will play in one of the feature games at the annual College Day in Napier on April 15 to be a strong side.
They will take on the Lindisfarne College 1st XV in one of the 3pm games at the Park Island-hosted tournament being organised by the Saracens club. The other 3pm match will see St John's College host Wanganui High School.
The 1.30pm games will see Te Aute College host Wairarapa College and Wairoa College host Freyberg High School. New Zealand's top four champions in 2017, the Hastings Boys' High School 1st XV will take on their Wellington College counterparts in one of the midday encounters while Dannevirke High School will meet Central Hawke's Bay College in the other.
Hastings Boys' High School's and Wellington College's 2nd XVs will meet in one of the 10.30am games and Karamu High School and Taradale High School will clash in the other.
