Alun-Wyn Jones won the race to start alongside captain Paul O'Connell in the second row with Phil Vickery and Gethin Jenkins to prop alongside England hooker Lee Mears.
McGeechan is set to name his Lions squad next month with full-back Lee Byrne, flanker Martyn Williams, lock Alun Wyn Jones, wing Shane Williams, props Gethin Jenkins and Adam Jones, scrum-half Mike Phillips, fly-half Stephen Jones and captain Ryan Jones as Wales' front-runners to make the tour.