I don't know anything about 300E's but I assumer it's a unibody car. If the frame was torqued then the whole car was torqued. So you're talking about something serious here.
I saw a Volvo 240 once which had been hit in the right front quarter panel and repaired - afterwards the windshield leaked. If you looked closely you could see body distortion around the edge of the windshield. The seal had failed because of this.
That car you're looking at might be OK, but it might have something subtle wrong with it that you won't pick up til you've had it awhile.