No more kitchen sinks!

 I'm running a campaign set in a mythic fantasy version of the British Isles, circa 860 AD. Due to the nature of the setting, there's many monsters and magic items that are restricted from use, and I absolutely love the effect that has in game. Given that I'm using a twist on a real world setting, the players immediately relate to it and have ideas of what can and should be done in the adventure, and by limiting monsters and items, I'm able to reinforce their suspension of disbelief.
  I think that adding too many elements from outside influences such as Tolkein's works, Conan and pulp adventure stories, etc., tends to shatter disbelief and revert players into a headspace where they know that they're just playing a game. Actually one of the issues running B2: Keep on the Borderlands is the baggage that creatures like Orcs and goblins bring, because they've been done so many times in so many other kinds of games.
  In fact one of my drives to play systems like Original D&D was its restrictions on player classes and races, and a lot of my advice for running spellcasters is to limit the specific spells that they have access to. I just didn't realize that it's better to limit all of these from a setting perspective and not a system one. That might explain the popularity of settings like Dark Sun and Ravenloft, which specialize D&D in their own ways.
  Rather than running a generic fantasy kitchen sink, I think its better to see the monster manual and spell lists as options that you must remove pieces of in order to fit your campaign. Most tables that I've seen just assume that everything that exists in the rule books also exists somewhere in the campaign world, but by creating a campaign world where some things cannot exist has conversely freed me up to run a more satisfying game.

Also as a side effect, using a map of historical Britain and Scandinavia has absolutely crashed my interest in fantasy maps. Fantasy maps are usually just pastiches of real world places anyway, with odd geography. I think it would be fun to run a campaign in Central or Eastern Europe as well, which would give access to most kinds of biomes.

Thoughts on Man-to-Man in D&D

Dragons fight as "4 heavy horse", which is simple on the mass Combat table, but unclear on Man to Man.
But wait, "Barding" is an armor option on the M2M table.
Dragon armor rating can simply be equal to Barding, with the appropriate number of Hit Die as referenced in D&D Book 2.
Then they also have that Achilles Heel of being shot out of the sky by a Hero on a roll of 12

I'm not a fan of multiple attack rolls. One "chance to hit" per attack is enough.
Hit Points should (and do) replace simultaneous hits with cumulative hits. There's no need to model extra attacks or anything on top of that.

Light, Heavy and Armored Foot troop types can map directly onto the Leather, Chain, and Plate armor types.
Light,  Medium, Heavy and Draft Horses are purchasable mounts in D&D, and with the addition of Barding can be armored.

In Chainmail, while flanking, the defender is hit as if he was one lower troop type. This correlates to a 2 step drop in armor type on M2M, with consideration given for a shield. It's also probably the origin of the "+2 to hit" rule in AD&D. In both AD&D and Supplement 1, the right flank gets no protection from a shield.

Digging into the Chainmail M2M rules has given me a new appreciation of Supplement I: Greyhawk as merely an attempt to translate Chainmail rules into the D&D chassis. The implementation is a bit tortured and some of the math is wrong, but its what we've come to expect from Gygax. I feel like a fuller explanation of the imported systems would have benefited the supplement, and apparently Gygax did too, as that's what he wrote in AD&D (and had issues describing it there as well)

House rules for D&D + Chainmail

The races: Human, Elf, Dwarf and Hobbit

The classes: Fighting-Man, Magic-User, Cleric

No multi classing, elves must choose a single class

Stats are rolled 3d6 arrange as desired, starting gold is 3d6x10 for personal equipment 

There are no hit points. A single hit is death for Man- type characters. It takes 4 concurrent successes on d6 for a Man to hit a Hero.

In almost all cases the Mass Combat Table will be used for combat resolution, the Man-to-Man Melee table will only be used for individual combat between Hero types and those rare cases when it applies against Monsters

Super Heroes may roll twice on the Man-to-Man Melee table to attempt to hit a Hero. Hero and Super Hero will use the Mass Combat table against Man characters.

The Man-to-Man Combat Table and D&D

I don't think the Man-to-Man table was ever intended to be used with D&D. The Mass Combat rules dovetail so nicely with both the Fighting Capability column and Monster HD that it does feel like the game was developed out of those rules, while the M2M table and D&D's level progression seem at odds with each other. Generally, every attempt to reconcile them has some struggles - the very first can be seen by Gygax himself in Supplement 1: Greyhawk.

I've seen some implementations that try to use the M2M table as the universal melee resolution mechanic for D&D, but I think that only works when two combatants are of the same type. For example, if two men are fighting or two heroes. In the case of Man vs. Hero or Superhero, it makes more sense to me to revert to the Mass Combat rules. I prefer squad combat and simultaneous hits over individual combat and tracking hitpoints over multiple rounds. Actually I don't even use hitpoints in the PbP game that I'm running, just the appropriate number of successes on d6 for a hit.

If you select the M2M table for use only against opponents of the same category, then you can still involve the "Fighting Capability" column of D&D for bonuses. For example, a "Man + 1" would roll 2d6+1 for his chance to hit another Man