Placing DD at 6 IPCs vs Cruiser at 10 IPCs increase the gap CA cost/DD cost: 1.67 compare to OOB 12/8 = 1.5 and make Cruiser a weaker unit.
The first idea of this thread is to put Cruiser at 10 IPCs for 1.25 ratio and BB at 18 IPCs.
Lowering DD to 6, implied to put Cruiser at 9 and BB at 15 IPCs.
That way, you keep OOB relative strength DD + CA vs 1 BB = 50% odds of survival.
As suggested in Redesign Thread: a SS5, DD6, CA9, CV12, BB15 also make easier all calculations purchase because changing 1 step above or below is 1 Infantry at 3 IPCs and Subs get the iconic 5 spot.
But, how far is too low because placing ships in water is what delay Allies and air cheaper or more cost efficient vs warships is the main way to repel fleet?
Classic TP D1 C8 vs Fg A3 D4 C10 was still efficient ratio but costly for Allies.
Placing both Cruiser and Fg at 10 is already helping UK fending off Lufftwaffe.
Going with advanced shipyard Tech can be tried too.
SS5, TP6, DD7, CA9, CV13, BB17
Carrier should still cost 14 to help BB compete with Cruiser it should be 16.