If the body is absolutely perfect, it may be worth it if you are patient enough to wait until you can find another 240 where someone rebuilt the engine, trans, etc, then either wrecked the car or discovered that it had structural rust. Buy this donor car for another $400.00, transplant the drivetrain into your perfect body, then you have a nice 240 for about $1000, once everything is done. It would not be worth it to buy this car and rebuild the engine, etc. because (in Boston anyway) decent 240s go for about $2500-$5000. If you do a complete drivetrain rebuild, you are going to exceed the cost of a good running complete car.
Colin