I've not done very well with keeping up with this thread. I'm sorry to say that your lengths for these ships are not right.
I've only checked A and B3 in detail, but:
1. The lengths for ALL the ships given in D'Eyncourt's Notebook are "between perpendiculars". That is from the rudder post to the point where the stem cuts the water.
2. A is 500ft pp, which is 152.4metres. You have it 152.4m overall length, and a pp length of 142.4m
Simple scaling of the length should be good enough 107% longer. Will you see that difference on eg gun barrels?
3. B3 is also 500ft pp, not 540, so that needs a bit more work.
4. The guns are L50, Hawkins guns (as on parts sheet?) were L45. I don't know if that's significant in pixels?
5. "the turret being slightly lighter than A, B1 and B2 with 3in armour." Not that it shows on the drawings, but the turrets for B3 and B4 were actually specified as 'armour: barbettes 4"; gunhouses 4" & 3" ' presumably 4" faceplate and some of the other [roof?, sides?] 3" so slightly lighter as you say.