There isn't really a better feat at 27 than blinding of speed. You could take epic damage reduction since you have haste, but my build just uses burst of speed.
The reason it is important to focus on the physical damage is because the elemental damage caps out really fast. Ranged weapons can't attack fast enough for just the elemental damage to do the work in epics. Shiradi is also not the best destiny of choice for that reason. You don't attack fast enough for the procs to become better than your base damage. Shiradi works well with repeating crossbows and magic missile because of the fast hits. Legendary Dreadnought and Fury of the wild will do more damage per hit, which is what bow users need.
Your build idea looks cool, but as far as I can tell it will be less effective at damage. My build gets dex to damage at level 2 and acid arrows starting at level 4 which is when the game becomes trivial because the damage is too high. Your build gets int to damage at level 3, and acid arrows at level 8. At that point, the acid will be the same, but once you get to quests like the archon chain or devils gambit where monsters have 3k HP, you won't have the damage to keep up. The same can be said for all of the level 18+ quests. This build will probably do fine in EN, shouldn't do epic hard until 24 when you have a thunderforged bow, and probably won't be able to do EE.
Most importantly, I could be wrong! My own personal policy is that you can't know how good or bad something is until you put 80 hours into it, which is how I came across this build. Do it up and let us know if it works