The other obvious improvements would be more of the same good Pirate cards already in the deck, and Piglet Pooh Pirate Captain
When I took out most of the cheat in effects like Exhume and Oath of Druids I left in Nightmare
The Immortal Sun Like several other artifacts in this ranking, The Immortal Sun earns its place not just by its card-drawing effect (which, if taken in isolation, isnt that great for a 6-mana artifact) but by the whole package it provides
The one thing I will note: you want to be playing around 27 lands with eight cycling duals, which limits you to Grixis or Esper instead of the traditional Temur or Jeskai
But restriction breeds creativity and finding the perfect reprint to fit a concept within a universe and deck theme can be extremely satisfying as a designer and, I hope, to you as the fan
Thats all the good stuff out of the way