Stark and his babes are in Marbella in the south of Spain to play two friendly games against the United States tomorrow and Canada on Monday.
Having seen his side narrowly fail to make the play-offs for next year's 2013 Euro finals in Israel, he is looking towards the next challenge.
And he is hoping McGeouch, who has just returned from a lengthy injury lay-off, and Watt can play a big part in their forthcoming campaign.
"I am delighted Dylan is back fit and available for these matches," the former Hoops midfielder enthused.
"It is disappointing to see any young lad get that type of injury (he broke his draw in a glamour tie with Real Madrid in August). He was performing really well in Celtic's first team. It was a big, big blow for him.
"We know exactly what he can do. We had him in the Under-19s for a couple of years and he took part in the Italy friendly. I know the ability he has. He has the potential to be a big player for us now in the Under-21s.
"I don't want to put too much pressure on him, but I would hope he makes the step up and becomes a regular starter. I know him and I know he is capable.
"You can never be sure how kids will handle the step up. But Dylan has confidence and any young lad who forces their way into Celtic's first team has good capabilities.
"To be honest, I wouldn't have expected him to get in about the first team as quickly as he has because Celtic have such a big pool of players."
Turning his attention to Watt, Stark added: "I am hopeful that Tony will be in the same bracket as Dylan and will be a really important player for the Scotland Under-21 side.
"The really heartening thing is that he has already got two Under-21 goals under his belt. Jordan Rhodes didn't have that at Tony's age.
"Now, I am not suggesting for a minute that Tony will be as prolific as Jordan. He has lots of other attributes to his game.
"But I am looking for him to be a leader for us and to take on the responsibility of being a goalscorer for us and hopefully thrive on that.
"Tony, too, has been on the porridge. As an old chairman of mine used to say: 'You are better with a good big yin than a good wee yin'. Tony is certainly that.
"I have seen him in games when he has been unstoppable with that power and pace of his. He can go a long way."