I thought Roger Maris's record was really tainted. He played at Yankee Stadium whose right filed line wa 298 feet. And he was a pull hitting lefty. Many of his home runs would have been routine fly outs in any other park. In the video below, you can see how short the distance was, and a short fence as well.

https://www.youtube.com/watch?v=4hSNO_PhSnI