If you're planning on being an Engineer, the
Force Reactive Disk is a great choice that synergises well with a Paladins kit. The item is BoE, so you can get hold of it without raiding yourself. Engineering also gives you access to useful consumables for pulling, something which Paladins distinctly lack in their base kit, as well as extra AoE damage consumables.
Cloak of Flames is another BoE that might be worth checking the AH for if you're willing to spend the gold for it.
For consumables, you should consider
Oil of Immolation if you don't need your potions for extra Mana and
Dragon Breath Chili if you don't need your food buff for stats.
Do remember though that Righteous Fury only gives you bonus threat based on your
Holy damage. As nice as the extra reflective damage is, it won't bump your threat up as much as you might think. If you want to ramp up your overall threat you really want to look at Spell Damage items.
As for your build, I'd move the points in Spiritual Focus to Imp. Judgement. Spiritual Focus is really an all or nothing talent, you either max it out and use it with Concentration Aura to heal without pushback, or you don't bother with it. Realistically, if you're healing yourself while tanking it means you're either going to die soon anyway or run out of Mana and lose aggro soon. While playing solo Seal of Light is generally enough to take care of most of your in combat healing needs by itself.
If you want to keep the points in Holy, Improved Lay on Hands reduces the cooldown of your most useful tanking cooldown by 20 minutes, which can let you get an extra use of it during longer dungeons. Unyielding Faith also lets you resist two of the most common aggro dumps mobs use since you can't just Berserker Rage out of them like a Warrior. It's not a super useful talent, but it will get you some milage at least.