That… Wouldn’t be very hard at all, honestly. The hardest part would be the clothes, because a pirate from the Golden Age of Piracy in the Carribbean Sea would be dressed for the tropics, not wintertime in New England, and most of his clothes just do not exist in the game. Doublets, pantaloons, etc.
That, and because of the way the game handles - or more accurately does not handle - multiple items being carried in one holster or dual-wielding, a proper bracer of pistols and a pair of swords, Edward Kenway-style, would be basically impossible to properly model.