Ahh yes spotted that. I still think that going purely off the numbers is a bad plan but your suggest rating alteration should make sense. Things like ships rates of fire was rarely as accurate as the sheer numbers, the German guns for example were big and powerful yes, but hauling those big shells manually would bite into a ROF very rapidly through exhaustion. It happened on RN ships with their lighter shells, there's only so many times you can lug a 28kg shell as well as another 16kg of propellant before your arms are simply knackered. A problem with many destroyers armament in WW2 because loading for the majority of them was manual.
For example hauling a standard 5 inch round for a German DD and its propellant 15 times a minute is a total of 660 kg. It would be impossible for that to be sustained without magical ubermesch replacing the loaders. Even spread across say 4 loaders (not sure of the size of the crew for the gun and its mounting) thats still 165kg per person over a minute. And the mounting is hand traversed and hand elevated. Any crew of any navy would be knackered after a few minutes of doing that.
Where as the RN guns are lighter yes, but so's the shell so whilst their ROF isn't as heigh, its more sustainable before you end out with gunners with arms like jelly.
This is why just going off raw numbers is a bad idea, but you're making the best of a bad situation.
How are you going to do the battle, as an escalating engagement or take it as if both big formations just meet in the channel and have a good 'ol punchup until one side is sunk or disengages?
I can see why you want to simplify it and give a general idea of what would (or could) have happened, but I have an awful feeling you're just stirring up a can of worms.
There is that fear too...especially from someone in the Wehraboo camp who's kept this thread going through sheer bloody minded obstinancy and refusal to accept reality....