It's tougher than a 240. Rust is always the biggest problem. watch out. I am familiar with the cars and I got fooled by a car that had what I thought was the original paint. It was a worn repaint that was hidding quite a bit of rust. Any way underneath/ behind the rear wheels and around the rear "clip" (?) and in the engine bay along the sides where the fenders are attached, around the headlights, is where to look for rust. If the price is right ($500) and there's competion buy and deal with it. If you have the time try to get it started and take it for a spin. Make sure you keep an eye out on the brake and clutch fluid, when a 120 has been sitting for awhile sometimes all the fluid runs out, I have had the experience of topping it up and not having to bleed the brakes or anything and the pressure came back and the system stopped leaking ( I think it leaked in the cold).
These are great cars and there were enough of them made that pretty much everything is available new or used (see if teh front rotors are nice and thick cause replacing them is like $150 per side).