Check the boot pan, and the battery tray. Also another bit there bad for is just under the roof at the top of the back seat area (hard to explain)

Mileage wise, make sure it has a good history (which should be stamped at services with the milage).l If theres no history with it then its unlikely the miles will be genuine.

Its worth getting the car up on the ramp to check the floor - it may need weilding, or it may have already had a good lot done. Nothing wrong with a bit of genuine weilding though, for the age of them its whats expected. I looked at one which the floor had actually been taped with duck tape to hide the holes, the guy couldnt believe I found him out.

A little bit of rust is OK but I mean a little bit.