In article .com,
gt wrote:

I own a 1960 Cessna 172 with 2500 hours on the airframe. It is not
rated for aerobatic flight, but the positive and negative G loads that
it is approved for far exceed the normal G forces associated with a
well-executed barrel roll.
Has anyone heard of this maneuver being performed in a 1960 172?

Not enough "energy" to be performed in level flight.
It can be done in a dive by a competent aerobatic pilot, maintaining
airspeed and 1-G loading throughout the maneuver.