Hi if you google lan chile seats the first selection is concerning the pacific islands on that site is the seat map for the 767-300 and the last row is row 38. However this is only showing 3 class configuration and Lan Chile do have 4 classes now on some planes, so this picture may be out of date.

As for Lan Chile, I flew Auckland to Santiago on an A340 in 2003 and they were great, food was ok, no problems

Hey there, the best thing to do is to phone the airline or email them. It could be quite hard to work out the seat numbers, like the above poster says the configuration coiuld be different.