If anxiety was a photo, check the ends of the band. If they're good pop the strut in and check how it seats (is the strut bent at all?), if it's not bent and seats okay you should be good. It can all be done with the trans in the car. Just had the same issue with a 727.
Option book says they had 3-on-the-tree and a 3-speed in the floor for '70 so it's possible the car used to be a 3-speed. Pedal looks to be laying on the floor so maybe they planned to swap to a 4-speed later on?
You can certainly run one on the street. My Ratrod and Duster both have Cheetah Valve Bodies in them one using a B&M shifter and the other the colum shifter.
Can 741/742 gears be swapped into a 489 case? I have a 3.91, 3.23, 3.55 set and a SG unit and planned to swap the 3.91's with SG in to replace my 5.38's.
Thanks, Kegan B.