Spider webbing on the paint is always the usual.
The L81 motor is junk and makes no power.
Transmissions were usually a TH-350 (Turbo 350 3-speed in auto form)
Personally I wouldn't try to stuff a big block in it, but a stroked small block would do wonders in it. According to GM the car weighs 3,345, so you would lighten it up with a few aluminum pieces and what not. What are you looking to get out of it? Auto-X, drag car, cruising car?