I add to what jeepboy had to say, check the rear foot wells too, if the car had been leaking rainwater internally, expect the footwells to have rotted through, which would be a lot of work to rectify. Also check the windscreen seals to be sure car is not leaking.
Around the engine firewall around the bonnet hinges, check that the metal there is good, and had not rotted through due to wet leaf accumulation.
my 2 cents worth. I learnt it the hard way.