Basically, the only upgrades you can really make are Garuda's Spine, Paragon's Crown, and melded Felt Trousers; so you're in pretty good shape. You're honestly only losing 3 STR and 2 ATK for switching from your current belt to a DEX one, and making the appropriate earring/bracelet swaps (Explorer's Earrings, Spinel Bracelet +1) should bring your DEX up to 287.

You should be at around ~450 or so ACC for Garuda, I usually run a little high. With your current setup I would swap out your Bracers with the Officer's Gloves and eat Aldgoat Steak or Smoked Raptor if you're able to afford it (you can eat Beef Jerky but your ATK is too low to really take full advantage of it so it's not really worth it). That should put you at about 448 ACC and 575 AP.

Don't spend too much gil on the trousers, try to shoot for an easy double, as Swordsman's Cry tends to be pricey, and you're gaining little for spending more on the upper tier IV's. I would hope Explorer's Earrings are fairly cheap since they're a common AV/CC drop, and the HQ Spinel/Electrum(situationally) shouldn't be too hard either, if you have a GLD friend.