Yeh, I played with it and got it to work finally. Its pretty much what you have. I didn’t realize they changed the theme and changed the CSS tag to entry-content from what it was before. Let me know if its wrong to use post-43…that’s what it looked like to be when I viewed the CSS.
This worked:
.post-43 .entry-content {
margin: 0 auto;
/* Changed on 10/10/14
max-width: 474px;
*/
width: 800px;
max-width: 800px;
}