I don't think that changing the position of the battery will make much of a difference in performance ... the only reason I've seen for moving the battery is to get more space in the engine bay to put in better air flow to the engine ...
I think it is a good idea personally, but you need to run some good think cables I imagine to maintain current strength. I really don't think that changing springs / shocks is really necessary, unless you wanted to of course, as passengers weigh more than a battery and they sit all over the place!
Simpler, and probably better overall, is just to replace your existing battery in the same location, with an Odessey Dry Cell unit, weighing only 5 kg or so. The reduction in weight of 12 Kg over your front axle will give some relief to the front suspension and will help it resist bottoming out.
Remember, these small dry cells will start your car, but if you leave anything on, anything, while the engine is stopped, the battery will run flat in a matter of minutes.
OK folks - you have convinced med not to go further with this idea. Thank you!
I may go for a dry cell battery in the original location when the current one needs replacement. It would've been interesting to experience the redistribution of weight (it's got to help some!), but I guess it's too much of a mod for a road car. Alfa should have though of this originally though