From what I have gathered, it will display the odometer from the gauge cluster. The odometer is not stored in the pcm on the lt1 cars and mechanical clusters cannot be "reset" via a scan tool. Most often, a sticker is placed on the driver door with the odometer correction if something like this arises. I am going to be doing the same swap as well. Cut the pig tail for the 97 cluster out of the donor car as well. You should be able to repin it but you need the connector. You can also use 93-97 bird clusters from what I have read.
http://www.cardomain.com/RidePost/20...evrolet-camaro
http://www.thirdgen.org/techboard/in...dash-swap.html