its hard to say what condition the box is just from the kms, it may have done 230'000km of hard work without servicing? it may have done 230'000kms of granny cruising and has been serviced every 12 months?
as already mentioned remove the pan and have a look and see if there is any crap or metal in the pan..

ive just fitted a 170,000km auto in my car and the fluid was clean and pan was clean, so that shows it has atleast been serviced regulary,

if you open your box up and the fluid left is really dark and smells bad, more than likely the box has not been serviced or it had been worked hard and over heated many times.
if your still not sure, just take it and use it as an exchange for a reco box and you wont have any worries.