I think he can let go of the hand brake. It doesn't seem to help as much once the tires leave the ground.

The last Offy Midget I saw race in competition was a restored car that Roy Caruthers drove for someone at the Speedrome. He ran it a few nights. It was either the Mid 80's or early 90's. I forget how he finished with it, but he did run a feature in it I believe.