If your even gonna crack that bitch open you might as well sleeve it an throw in some forged pistons, the need for speed is addictive and as long as you have the motor out and some play $$$$ you won't be held back from future endeavors.
From my moderate knowledge of ECU's and engine management, the difference in displacement is negligible as far as the additional fuel requirements, so the 3 litre ECU should trim itself out. The injectors in a 3.0 and 3.2 are the same size (240cc or 270cc, I forget, they are pipsqueeks though compared to the big dogs on FI setups) They are just a different type in the OBDII (3.2) ECU, they are saturated, which is essentially a flurry of micro-pulses as oppsed to the peak-hold injectors used by the 3.0.
So anyway , the moral of the story is do whatever you want to the block, upping the displacement to 3.2 is only an additional 6% of air you need to squirt gas in for, that would be similar to running 1 PSI of boost, for which no modification to the ECU or fuel system should be necessary.
