I think since Broke's training emphasised accuracy which increased the chances of hits, perhaps return zeroes and redraw, although this is a big advantage. It's essentially the 'Good Aim' card but as a permanent effect. Perhaps allowing the 'Good Aim' card to be used 4 or 5 times per engagement may be fairer, or perhaps for the first 4 or 5 broadsides (after which accuracy would decline given fatigue, heated gun barrels etc).

I think selecting between chits already drawn allows for upgrading damage, and while accuracy was increased, damage was probably still dependent on lady fortune to an extent...

I have ordered Broke of the Shannon book and will probably order the reprint of the Evolution of Naval Armament which discusses gunnery: https://www.gutenberg.org/ebooks/56777

I love rabbit holes!