First, do you know if the governor was removed when the MVB was installed? If so, it'll need to be replaced before installing an auto VB.

The '74 isn't an ideal swap into a '67, lots of fluid circuit changes were made starting in '74.

The stop tabs have definitely been removed, they're needed.

On the pressure regulator, measure from the VB side of the steel spring retainer to the casting...should be in the 1 1/4" to 1 1/8" range.