I like the increased range for shore batteries. I've been pondering shore guns for some time, and haven't suffered any epiphanies.

Here's what I've got so far; the increased range. A stronger initial hitting strength that drops off quickly (batteries tended to have fewer but heavier guns). Extremely large Burden, like 12-20, to reflect guns being farther apart and stone construction. Flooding, rudder, mast, etc. hits tying in to some crucial part of the facility, like the magazine, shot furnace, etc.

As to plunging fire, perhaps this should only apply to fixed targets with mortar ships? Even when firing from an elevation in this time period a conventional cannon would be trying it's best to do straight line-ish. What about having a blind spot that the guns can't decline to?