3T Kakashi with War Arc stamina could potentially take this alone. Giving him an equally skilled 3T fighter to back him up makes this a relatively easy win.
Kakuzu starting with hearts out is a detriment to him in this match-up. You say that Kakashi and Itachi have "no knowledge" yet have Kakuzu with all his hearts out at the beginning of the match, essentially damaging his advantage of his opponents not knowing his abilities. With his hearts out, Kakuzu won't have a chance at blind-siding them when they think he is dead like he did to Rasenshuriken Arc Kakashi.
Kakashi and Itachi are faster than Kakuzu by a good margin, and both are capable of utilizing Kage Bunshin, diminishing Kakuzu's number advantage. The hearts have not been shown to be impressive when they are not overwhelming someone with their numbers; individually, they should not be a threat. They appeared a threat against Kakashi because not only was he worn out physically and exhausted but he was also outnumbered. He was dodging / countering elemental canons while initially holding off Hidan as well as keeping an eye out for Kakuzu himself.