The voltage is mostly a question of "what you can get" and physical size, and a 350V will be fine - in fact you commonly see both 350V and 400V used.
Obviously depending on the reliability of your electrical supply, a 400V one would give a greater range for mains errors.
Is your mains actually 230?, or is it just nominally 230? - the UK stayed on 240, and the rest of Europe on 220, although all are 'nominally' 230. The 230V rating is for equipment, not the actual mains voltage.