What is regular highway cruising speed of a '62 Ford Falcon, 170 CI motor, stock 2-Speed Ford O'Matic ?

I recently bought this car, and drove it home. It wouldn't go over about 50 mph during the drive, and I ended up having the transmission rebuilt by a local shop. I got the car back and it still won't do much over 55 mph. This really seems weird. I understand it was 1962, but cars had to have been designed to go a little faster then that. (And don't tell me to lose the 2-Speed, it ain't gonna happen!)