I'm not all that clear on the overall situation here, my quick assessment is if it's basically sheet metal work, then by all means go ahead with the project. If the engine is sound (how many miles? manual or automatic transmission?) and the car has generally been maintained well, then that's further on the "+" side of things. On the other hand, if the previous owner's loss of control leading to the crash also reflects his or her general regard for the car, then the problems may well multiply beyond it's being a project with a good end in sight.
Back to the engine, this would be a 6-cylinder in this car, right, an M20? I don't believe these were directly sold in the US, possibly it's a gray market car, so you just might want to run a few more tests to verify that the engine really is in good shape, I really don't know if there were any particular issues with this engine, such as the ceramic water pump impellers with the M50 sixes.