Take the speedo drive out of the transfer box, and try the cable in the square, my bet is that it is too big...
I swapped the BW transfer box to an LT230 and found exactly this issue, I used the gear from the BW box in the end, which fits fine, and the speedo isn't THAT far out, and I am on 33" tyres.
TBH, going from 205 to 235 tyres makes not a lot of difference to the speedo, maybe 8% under reading...