AC by Location

I was flipping through my copy of Exquisite Corpses by Stefan Poag and couldn't help but wonder how games might play out if combat accounted for the AC of combatants Head, Torso and Legs. It is easy to get those scores for Exquisite Corpses created monsters and one can figure it out for monster with single score Ac score fairly quickly but it can be a bit tricky for armored character types.

The following has a bunch of fiddly bits that can of course be used or ignored as the campaign dictates. AC scores are all listed as a plus to AC score to work with pretty much any AC format.
I haven't tried these in play myself yet so the impact is unpredictable.

Head-Torso-Leg AC

(the chart is larger if you click on it)
Each subsection provides multiple exclusive selections for each general location.
By example: You can't wear two hauberks, or mail gloves and a gauntlets but yuo can wear a coif and a helmet or Leggings and a kilt.

Hauberk and Cotte may be combined, Hauberk and Cuiras may be combined.
Cuiras and Cotte may not be combined.

There are a number of penalties listed in each armor section. The penalties are meant to reduce the chance of success for ability check based mechanics. They would probably work fine in a d20 or save based action resolution as well.

Combat Notes-
Additional fiddly bits to combat are invited if one uses even the three simple hit locations of Head, Torso and Legs here are some suggestions.

Hitting Target in the head-
Is allowed if you have a longer weapon then your foe does.
Is allowed if you have initiative over a foe.
Is allowed if you have surprised a foe or are attacking from behind.
Missile attacks from beyond short range are made at an additional penalty of -2

Hitting a Target in the head with a die roll of 19-20 (if other scores can hit) requires many targets to make a save or be stunned until end of following round.

Hitting Target in the Torso-
Is the base default no special conditions required.

Hitting Target in the legs-
Is allowed with no penalty if you have a long weapon.
Is allowed with no penalty if you have surprise or are attacking from behind.
If in melee and you miss with a to hit die roll of 1-5 when making a leg attack (except for conditons above) your opponent gets a free melee attack against you.
Missile attacks from beyond short range are made at an additional penalty of -2

Hitting a Target in the legs with a die roll of 19-20 (if other scores can hit) requires many targets to make a save or be knocked prone (armed foes will drop weapons).

Notes on AC
Best Ac of Head
Great Helm, Metal Gorget and Mail coif gives ones head an AC of -2 (21)
cost 70 g.p. perception -6, speech -5

Best Torso Armor
Mail Hauberk, Ribbed Cuiras, Plate Bracers and Gauntlets
provide a torso AC of -6(25)
cost 350 g.p. maneuver -9, manipulation -8

Heaviest Leg Armor
Mail Leggings, Mail Kilt, Plate Taces, Plate Codpiece, Plate Greaves and Plate Saboton provide a leg AC of -6(25) with a move penalty of 30
cost 195 g.p

To buy best suit of overall armor would cost: 615 g.p.

A DM is of course free to assign a Maxiumum possible AC in a specific location as fits the rule set being used. Players should be aware of such restrictions to avoid over-buying armor.
Some folks don't like nonmagical AC better then 2,1 or 0 and I can agree.

Magical armor and the hit locations-
The best magical AC of any piece in a location improves AC, multiple magical bonuses to pieces do not add up.