I think I saw this thread like 6 months back... weird...
Anyway, there is no place that I know of that has these numbers, but check monsters of the appropriate CR and compare those numbers to your PCs. See what are the chances to hit them of the guys with good BAB and you are good to go. 3/4 people should hit less often and don't bother with balancing ACs for 1/2s. I know it is a little extra work, but I have no idea where to find what your are looking for.
A good rule of thumb: Attack bonus for good BAB classes can be approximated with the following formula:
Lvl x 1.66 + 3 (Round down)
So, a lvl 1 fighter will have an attack bonus of around +4 (STR or DEX 16 and +1 from the BAB; No feat) and a 16 lvl fighter will have around 29 (+16 from the BAB, +4 from STR/DEX, +3 from the magic weapon, +3 from weapon training, +2 for the Belt of +2 to STR/DEX and +1 for the feat).
A more optimized PC will have a BAB that is a couple points higher than that (say, he takes weapon focus and greater, gets a magic weapon with the highest "+" possible instead of other enhancements, etc...) but not that much.