AFAIR you just need the breastplate for the dwarven king to give you the helm.
If you hold the Shift key down (or enable Caps Lock) you can move the screen focus with your mouse to see or toss stuff further.
Either try again with the teleporter stone, or toss the breastplate in and let the guards take the rest of your inventory.
You can also just kill the guards before they take your stuff and walk in. If you use an area effect spell that does not need a target (such as Poison Cloud) near but not directly on an NPC, it will do damage but not count as an attack, so they will not turn hostile and you will not loose any reputation. Most or all essential NPCs should be protected from death (un-named NPCs should be safe anyway).
Welcome to the forum.
