I think both their macho egos would have guaranteed a war, sooner or later they'd have started to trade as it's in their nature to do so (neither man was good enough a boxer to outclass the other)
Froch' s size wouldn't come into it either, at the very tail end of a hard career Eubank more than held his own against a rock hard Cruiserweight in Carl Thompson over 2 fights one of which he fought 4-5 rounds with one eye.