Removing an Océan-class ship's upper gun deck

How much speed and lower-gunport clearance would an Océan-class ship gain by losing its upper gun deck?

Only a modest rise in gunport height and perhaps around a knot of speed are suggested.

Removing the upper gun deck is expected to raise the lower gunports somewhat. The speed estimate is tentative: one or two knots is suggested, then nearer one knot. The intended benefit is using the lower guns in rougher seas.