I'm one of those wacky people who actually likes the weapon vs. AC tables from Greyhawk. That's because the table has its origins in Chainmail and I'm forever drawn to the notion of making OD&D combat more consonant with the rules of its precursor game.
I'd like to include a similar table in Dwimmermount when/if I get around to publishing it. I have noticed, however, that OSRIC makes no attempt include such rules, which makes me think that it might be difficult to reverse engineer them in a legal fashion. Spellcraft & Swordplay does include such rules, but it uses a different AC numbering system (in part, I suspect, to avoid the very problem I'm grappling with), so it doesn't offer me a good model to emulate.
So, does anyone better versed than I in the niceties of retro-cloning have any advice? My gut instinct is simply to create tables that are similar but not identical to those in Greyhawk. The table basically boils down to -3 to +3 modifiers versus particular armor classes. My own feeling is that -3 and +3 are in fact too large as modifiers anyway, so I'd probably just cap the penalties and bonuses at +/-2 anyway. Would simply doing that (i.e. changing all the +/-3 references to +/-2 references), along with rearranging the presentation of the table (so it's alphabetical, for example) be enough to retro-clone it properly? Or have I missed something important?