I wouldn't mind seeing Couture-CC fight right now, it's a novelty fight and a few years too late but it won't effect rankings, the loser will likely to retire and I'm sure the fight will gain some interest. As for Mirko-Chuck, I'm sure Chuck would use his wrestling, he would stand with CC for a while but that would be just to distract him from a TD. Especially these days Chuck's Chin isn't doing so well.
At their primes CroCop is the better striker; although the cut would be new to him. CroCop also had pretty good takedown defense, so it should be his fight.