Nice idea, stevedave, looks great. ANYTHING is better than the pixelated original plastics. The pirate flag is much more dramatic. However, to my eye, there is too much black and it doesn't fit with the rest of the game. You might try something like the sketch below. Maybe ocean waves instead of the blue?
Maybe you could turn the cannons toward the ship like HOOKED suggested. They could straddle the return lane with the front wheel on the sling plastic. Would be really cool if a red LED was sticking out the end of the cannon and it lit every time the ship was hit.