without doubt, the 1.1A is the better one to get if you wanna overclock.
it will easily run at 133 fsb. (the 1.2 should also do it, but it may not).
the 1.1A stands a good chance of getting to around 140-145 fsb. which is roughly the same speed as a [email protected] fsb, but the extra fsb bandwidth will give the 1.1A more performance.