Normally in a game, I would go Trinity Force as first to buff up the pistol damage, AP scales a little and average stats, then its Statikk Shiv because it provides me even more pokes as GP can't go in 1v1 without warmog. Then I'll go Warmog's Armor followed by Infinity Edge. Well, it actually depends on the playstyle of the player on whether which item you go through. This is just my opinion though.

As for your regular build, the build is good but you need to flip the build order a bit. Unknown to a lot of people, the correct build order should be IE first followed by Warmogs. Your current build doesn't build tanky fast enough. Attack speed should be VERY late, third item or later. This is important because Gangplank isn't manly enough to close in and fight with the likes of Darius or Xin Zhao, to name some bruisers. In which case all that attack speed will be useless. So you need to prioritize AD and then tankiness first in order to keep your Parrrley damage scaling well, while at the same time being able to hold your ground if you need to fight.

Remove the supplank build. You're not talking about it in the guide at all that's a first, secondly supplank has been unviable since forever. Guess which meta support he is essentially a worse version of. That's right, Sona.