The 2009, 1997, 1993 and 1989 Lions boss is expecting some headline grabbing calls from his successor and he reckons full back and wing could be ripe for those kind of brave inclusions.
"Selection is a personal thing for a coach and he will have his own feel about the different players and combinations he is after," McGeechan told Sky Sports in his role as an ambassador for Lions sponsor FirstCape wines.
"However, I think at full back or the back three there are a couple of possibilities for a surprise selection.
"Warren might just look at the hard pitches around Australia and decide that a certain player might just be right for the conditions.
"I think the coaches will have taken a long look at the squad since Christmas, and from the end of the Six Nations they will have had the top 25 or so sorted.
"They will have then been taking a really hard look at the last 10-12 players as those are the ones that can make the tour.
"I'm sure there will be a couple of surprises."
Gatland certainly isn't short of options out wide and at the back, with a whole host of big names and potential bolters battling for what is likely to be between six and eight spots.
Ireland's Rob Kearney appeared a shoe in for a squad place prior to the start of the season but Leigh Halfpenny now seems to have secured his own inclusion at 15 after a fine international campaign, while Stuart Hogg repeatedly shone for Scotland to do his chances of a call up a world of good.
England's Alex Goode offered Stuart Lancaster's side a second playmaker at the back thanks to his experience as a fly-half, with the versatile Mike Brown impressing out of position on the wing and Ben Foden providing another quality option after an early season ankle injury halted his progress.
As for the out and out wings, Alex Cuthbert was outstanding in Wales' Championship-clinching win over the English, while countryman George North seems to be in most people's Lions squad thanks to his game-breaking abilities and strong finishing.
Ireland's 2009 Test Lion Tommy Bowe has shown glimpses of his class after recently battling back from four months on the sidelines and Gatland has repeatedly admitted that Simon Zebo and Craig Gilroy have caught his eye.
Scotland duo Tim Visser and Sean Maitland proved they know their way to the tryline in their debut international campaigns, while Chris Ashton looks to be getting back towards his best for Saracens after a frustrating few months.
And then there's London Wasps flyer Christian Wade, uncapped by England but with plenty of raw talent. He certainly impressed Gatland and co when the Lions hierarchy saw him score a brace of stunning tries in the European defeat to Leinster a fortnight ago - maybe he could be the first man to represent the Lions before playing for his country since Will Greenwood achieved the feat under McGeechan's stewardship 16 years ago.
Whatever combination Gatland selects in his back three, McGeechan insists the key will be getting the balance right across the squad as a whole.
The legendary Lion knows the importance of picking the right blend of youth and experience and he believes Gatland will follow that principle early next week.
"For a coach it's a big dilemma: your experienced players have been there and done that but have they got another series in them or a last Lions tour?" added McGeechan.
"It's a similar dilemma with the younger players: will they be able to build on their game and step it up a level?
"If you look at the likes of Jamie Heaslip and co four years ago we saw their games really come on."