I believe 69 minutes is legal (can't remember the exact cutoff).

Whether you want to chance it depends on your particular circumstances.

I always allow at least 2 hours because: 1. flights from my originating city frequently depart 30 or more minutes late; and 2. I want to arrive as early as possible the next morning because of tight train connections to my final destination.

You might check the on-time record for your initial flight. Then you weigh the inconvenience of a 4-hour layover against the probability of missing your int'l flight and the inconvenience that might cause. Be sure to take into account the season in which you're flying and the chance of the later int'l flight being full.