AD&D lets you convert IQ to Intelligence (divide by 10), so that means we know the Intelligence, and thus the AC bonus, of real-world geniuses.
Richard Feynman: IQ 126.
AC 11
Bill Gates: IQ 160.
AC 13
Marilyn vos Savant: IQ 228.
AC 15
More: http://blogofholding.com/?p=4069
We could figure out Strength scores if we knew how much people could bench. Is there any celebrity for whom we know both IQ and maximum lift weight?
This is in the 4e section, so I'll mention things relevant mainly to 4e.
IMO, IQ should not be Int x 10. IMO, a person with Int 10 has IQ 100, but for every 2 point increase in Int, there's only a 5 point difference in IQ. (So John Gotti, IQ 105, has Int 12. Otherwise one of the most successful mob bosses doesn't even have an Int bonus of +1.)
A person with Int 18 would have an IQ of 140, which puts them into "gifted territory". I believe this represents less than 2% of the population. I'm sure someone who can do probability math better than myself can tell me how often you roll an 18. I don't think gifted people (Int 14 under an older system) should be nearly that common. The typical expert sage would be gifted under that system!
Second, NPC AC scores are based on role and level, nothing more. They're not PCs, only PCs are PCs. Albert Einstein would probably be a high heroic level minion (roughly 6-9th level) with a skill boosting power:
Minor Actions
Eureka! * Daily. Effect: Einstein gains a +5 power (?) bonus to the next Academics (physics) (?) check he makes before the end of his turn.
I put ? in the equation because I'm not sure if a power bonus is reasonable (the henchman with the equivalent power was an item bonus, but that's because henchmen are basically items) and I had to make up a skill too!
Let's make Einstein 8th-level (based on his age; I came up with that using two separate methods, but I'm not using 3.x-style aging bonuses/penalties), and assign his base stats as 17 14 13 12 10 8, a bit behind the curve for PCs. (He has a 17 because humans get a +2 stat bonus.) By 8th-level he has an Int of 19, which is genius level. His Academics check (a special Int-based skill) is normally +13 (he can hit a 23 without trying), and once a day he can get a +18. The hardest questions Einstein is likely to try to answer is DC 30, I believe, which is a hard question for a 15th-level sage. Einstein can hit that mark 40% of the time once per day (how often does Einstein create a new theory?), even more if he has some kind of "master tool" like a really good physics library. (I think a good quality mundane library might give him a +2, but he'll need to spend an hour researching to get that kind of a bonus.)
I'd make him a controller, or maybe controller [leader] minion, if he has some kind of advisory power. That would give him an AC of 22, which is quite high, but remember, it takes only one hit to do him in. (His Reflex defense would probably be pretty high, because he can "think fast", but there's no reason you can't give him an "aged" trait to limit his AC, Fort and Reflex.)
Note that a bard or paladin could easily do better using social skills (Words of Friendship and Astral Speech), since they can take feats like Skill Focus. Unlike Einstein, a typical PC would have magic items.
If anyone cares, I've also statted "Arnold". There's a henchman trait called "Strong" that lets a character carry an arbitrary amount of stuff (and maybe lift a bunch of stuff, too). In Arnold's case, I gave him Extreme Effort, the d20 Modern power, a move action at-will power that gives him a +5 bonus to the next Strength or Athletics check (not attack rolls!) he makes before the end of his next turn. This would let Arnold "pump himself up" and temporarily lift a much higher amount of weight than he would normally be able to. And of course, Arnold has a high Strength score in the first place, so his Athletics bonus is quite high.
