I own a LongEz with an O-320 and if I were to tackle my battery and wiring system in its entirety, I would take the battery out of the nose and mount it nearer to the engine. Probably, just behind the passenger's head or below his/her thigh support. With this configuration I see at least two significant advantages. 1)Weight and length (resistance) of thick cable runs to the engine is minimized. 2)It helps to keep the electrically noisy cables away from noise-sensitive wiring to the avionics. It also puts the battery in a warmer location than the notoriously cold nose, for greater performance. By the way, I use an Odyssey PC625 battery which is considerably lighter than the standard Gill25 battery originally used, and can be mounted in any orientation. I'm pretty sure I could get away with an even smaller battery, if I were so inclined.
The battery in the nose was good for weight and balance when the plane was originally designed and built to plans. However, considering the customizations in most planes, with electric retract, more heavily instrumented panels, lighter alternators, starters (making heavier O-320s more practical), lighter cowlings, disuse of heavier aluminum spinners, etc., I think that even if some additional nose ballast was still required for W&B, the advantage of a more reliable electrical system is worth the penalty. Furthermore, this ballast could be smaller and placed even more forward than where the battery would fit.
You didn't say what engine you have or if you have a standard or lengthened nose section, but you will still be able to get your CG correct with the battery out of the nose. I have confidence you will do a proper W&B.