I have Video tape from the 1960s of the Lockheed L286 doing loops , rolls and other neat stuff.Very impressive.The Lockheed XH-51A also did some incredible flying , like flying close to 300mph in nap-of earth.
The lockheed test pilots wanted to do
Aerbatics with the AH-65A Cheyenne but the
Army wouldnt allow it.
I also have a video tape of the German pilot by the last name Zimmerman doing things in BO-105 that was simply incredible.
He ended up dying in a crash a few years later.
I beleive the Bell 222 with the 680 rotor did rolls and possibly loops and lots of other interesting Aerobatics.
The CH-53A did loops and rolls but was at a very low gross weight and needed the rotor head and drivetrain repaired/replaced.
I know Sikorsky did some amazing stuff with the S-67 Blackhawk during its testing
until it was crashed at the Paris Airshow in 1973.