As Aber pointed out, you're being a little pessimistic here. Remember that Graf Spee's guns were probably more powerful, being a lot newer - and during JW51B a bunch of destroyers stood up to Hipper and Lutzow including taking main armament hits (the Soviet naval authorities in Murmansk didn't believe who they had been fighting until they found the shell base from IIRC one of Hipper's guns and measured it for them). The other point is that bad weather probably favours the RN - they're likely to have radar, which the Argentinean dreadnoughts certainly will not have.This is assuming that the engagement is at range. Bad weather can come in, and 12" guns are ruinous when they hit anything less than a battleship. Yes, cruisers could win--but perhaps not, as well. ONE 12" shell has the potential to make a cruiser go BOOM! Unlikely, but something to be aware of--the battleship only need get lucky once.