Mundine, who was stripped of his WBA interim junior middleweight title after refusing to fight Austin Trout, says McKart is merely a launching pad to land him his main target of Mayweather.
"I've got to start somewhere ... this is a launching pad to bigger and better things," he said.
"They can feed me all the chihuahuas they want - I want the big dogs because I'm going to stomp on them.
"I'm going for Mayweather, man - that's what I want. He's the best - I want him... and I'm just going to keep beating whoever they put in front of me 'til I get him.
"I believe I'm on his level. He's a great fighter - one of the best in our era - but I want the chance to see what I can do against him."
Mundine, who with his trademark bravado proclaimed: "I believe I'm the best athlete of all time", admitted there would have been more money in a re-match with Danny Green but he was more concerned with breaking into the US boxing scene.
"Green's the bigger-money fight, but this is about cementing my legacy now," said Mundine, who turns 37 next week.
"I've been there, done that ... I want to go over there (to the US) and wreak havoc on every opponent I face.
"At the moment, boxing is a two-man show. You got Floyd (Mayweather) - you got Pac (Manny Pacquiao). I want to make it a three-man show."
Mundine admitted a points decision against McKart would not be enough to get him noticed on the competitive US scene. He needs to "make a statement".
And should he lose, that could signal the end of his boxing career.
"I want to stop it in six or seven rounds," he said.
"I feel that there is no reason to go on if I can't get past him.
"This is my first opportunity to shine under the lights in the mecca of boxing, Las Vegas."
-AAP